Polyendocrine Metabolic Ovarian Syndrome (PMOS; formerly PCOS)
Polyendocrine metabolic ovarian syndrome, formerly polycystic ovary syndrome, is a common endocrine-metabolic disorder characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology or elevated AMH in adults.
Polyendocrine Metabolic Ovarian Syndrome (PMOS; formerly PCOS)
Polyendocrine Metabolic Ovarian Syndrome (PMOS), formerly polycystic ovary syndrome (PCOS), is a heterogeneous endocrine-metabolic disorder characterised by a combination of hyperandrogenism, ovulatory dysfunction, and polycystic ovarian morphology or elevated AMH in adults. It is the most common endocrine disorder in women of reproductive age and a leading cause of anovulatory infertility.
The 2026 global consensus process renamed PCOS to PMOS because the old name overemphasised "cysts" and the ovary. The ultrasound finding is not pathological ovarian cysts; it represents multiple arrested antral follicles. Polyendocrine captures androgen, insulin, neuroendocrine, and ovarian hormone dysfunction; metabolic captures the lifelong insulin resistance, diabetes, cardiovascular, liver, and sleep-apnoea risks; ovarian preserves the link to ovulatory dysfunction and fertility [8][9][10].
The internationally accepted diagnostic framework remains phenotypic and exclusion-based. In adults, the 2023 International Guideline requires two out of three criteria after excluding mimics [1][2][8]:
Two out of the three criteria (Rotterdam consensus):
Important Nuance
PMOS/PCOS is a diagnosis of exclusion. Other causes of hyperandrogenism and anovulation (e.g., congenital adrenal hyperplasia, androgen-secreting tumours, Cushing's syndrome, thyroid disorders, hyperprolactinaemia) must be ruled out before making the diagnosis. Many students forget this step.
2. Epidemiology
- 5–15% of women of reproductive age worldwide (varies by diagnostic criteria used — NIH criteria give ~6–8%, Rotterdam criteria give ~10–15%).
- One of the most common reasons for gynaecology outpatient referral.
- In Hong Kong / East Asian populations, prevalence estimated at ~5–10%. The phenotypic expression may differ — Asian women with PCOS tend to have lower BMI but similar metabolic derangement (so-called "lean PCOS"), higher insulin resistance for a given BMI, and potentially less overt hirsutism (due to ethnic variation in androgen-dependent hair growth) [3].
- Typically presents in late adolescence to early reproductive years (15–30 years).
- Symptoms often begin around menarche or shortly after.
- May persist into the perimenopausal period, though hyperandrogenism tends to attenuate with age as ovarian androgen production declines.
| Category | Risk Factor | Mechanism / Explanation |
|---|---|---|
| Genetic | Family history of PCOS | Polygenic inheritance; first-degree relatives have 20–40% risk; candidate genes involve steroidogenesis, insulin signalling, gonadotropin regulation |
| Genetic | Family history of T2DM | Shared insulin resistance pathways |
| Obesity | Central / visceral obesity | Adipocytes release large amounts of FFA → insulin resistance; adipocytes release adipokines → insulin resistance [3][5]. Hyperinsulinaemia then drives ovarian androgen excess. ~50–70% of PCOS patients are overweight/obese. |
| Insulin resistance | Intrinsic insulin resistance | Present even in lean PCOS patients — this is intrinsic to PCOS, not solely obesity-mediated |
| Ethnicity | South Asian, Middle Eastern, Indigenous Australian | Higher prevalence and more severe metabolic phenotype |
| Environmental | Sedentary lifestyle, high-glycaemic diet | Worsen insulin resistance → exacerbate hyperandrogenism |
| In utero exposure | Excess prenatal androgen exposure | Animal models suggest fetal androgen programming of the hypothalamic-pituitary-ovarian axis |
Hong Kong Context
In Hong Kong, the prevalence of PCOS is rising in parallel with increasing obesity rates and westernised dietary patterns. However, a significant proportion of PCOS patients in HK are lean (BMI < 23 by Asian criteria) — don't dismiss the diagnosis just because a patient is thin. Insulin resistance can be present without overt obesity in East Asian populations.
4. Anatomy and Function
Understanding PCOS requires understanding the hypothalamic-pituitary-ovarian (HPO) axis and the role of insulin as a co-gonadotropin.
Normal folliculogenesis (the "two-cell, two-gonadotropin" model):
- Theca cells (outer layer of follicle) respond to LH → produce androgens (androstenedione, testosterone) from cholesterol via the steroidogenic pathway.
- Granulosa cells (inner layer) respond to FSH → express aromatase (CYP19A1) → convert theca-derived androgens into oestrogens (mainly oestradiol, E2).
- In each cycle, a cohort of antral follicles is recruited. Rising FSH selects a dominant follicle (the one with the most FSH receptors and aromatase activity), which produces high E2.
- Rising E2 triggers the mid-cycle LH surge → ovulation.
- The ruptured follicle becomes the corpus luteum, which produces progesterone to support the secretory endometrium.
Key point: Normal ovulation depends on a delicate balance of FSH, LH, androgens, and oestrogens. PCOS disrupts virtually every step.
The "polycystic" ovary contains:
- Multiple small antral follicles (2–9 mm diameter), arrested at the pre-antral/small antral stage, arranged peripherally ("string of pearls" pattern).
- Thickened, fibrotic ovarian stroma (due to chronic LH stimulation → stromal hyperthecosis).
- These are not true cysts — they are follicles that were recruited but failed to achieve dominance and ovulate due to the abnormal hormonal milieu. They accumulate over successive anovulatory cycles.
5. Aetiology and Pathophysiology
PCOS has a multifactorial aetiology involving genetic susceptibility, intrinsic ovarian steroidogenic abnormalities, neuroendocrine dysregulation, and metabolic/environmental factors. There is no single causative mechanism — it is a self-perpetuating vicious cycle.
5.1 Core Pathophysiological Mechanisms
The ovary is the primary source of excess androgens in PCOS, though the adrenal contributes ~20–30%.
Why does the ovary overproduce androgens?
-
Intrinsic theca cell dysfunction: Theca cells in PCOS ovaries have upregulated steroidogenic enzymes (especially CYP17A1 — 17α-hydroxylase/17,20-lyase), leading to exaggerated androgen synthesis in response to LH stimulation. This is a fundamental, possibly genetically determined defect.
-
LH excess and abnormal GnRH pulsatility (see below): Chronically elevated LH stimulates theca cells to produce more androgens.
-
Hyperinsulinaemia (see below): Insulin acts as a co-gonadotropin — it augments LH-stimulated androgen production by theca cells. Insulin also:
- Suppresses hepatic production of sex hormone-binding globulin (SHBG) → ↑ free (bioavailable) testosterone.
- Potentiates adrenal androgen secretion.
-
Adrenal contribution: ~50% of PCOS women have elevated DHEA-S (dehydroepiandrosterone sulfate), indicating adrenal androgen excess. The mechanism is not fully understood but likely involves dysregulation of adrenal CYP17A1.
-
In PCOS, GnRH pulse frequency is increased (faster pulses), which favours LH synthesis and secretion over FSH.
- Why? GnRH pulse frequency determines the ratio of LH:FSH. Fast pulses → ↑LH; slow pulses → ↑FSH. In PCOS, the GnRH pulse generator is "set" to a higher frequency.
- The reason for this is partly due to reduced progesterone negative feedback (because anovulation → no corpus luteum → no progesterone → nothing to slow GnRH pulses) and partly intrinsic hypothalamic dysregulation. Excess androgens may also be converted to oestrogens peripherally, contributing to altered feedback.
-
Result: ↑LH, normal-to-low FSH, elevated LH:FSH ratio (often > 2:1)
- ↑LH → ↑theca cell androgen production → hyperandrogenism.
- Relatively low FSH → insufficient stimulation of granulosa cell aromatase → follicles cannot convert androgens to oestrogens efficiently → intra-follicular androgen excess → follicular arrest (follicles cannot develop past the small antral stage) → anovulation.
- Low FSH also means no dominant follicle is selected → multiple small follicles accumulate → polycystic morphology.
This is present in ~70–80% of PCOS patients and is a key driver of the syndrome.
Insulin resistance in PCOS is contributed to by:
- Central obesity → adipocytes release large amounts of FFA → insulin resistance; adipocytes release adipokines → insulin resistance [3][5]
- Intrinsic/post-receptor signalling defect in insulin signalling (selective insulin resistance in metabolic tissues, but ovarian tissues remain insulin-sensitive → a paradox).
- Physical inactivity → ↓AMPK activation → ↓glucose uptake + ↓FFA metabolism [3]
Why does hyperinsulinaemia worsen PCOS? (The vicious cycle)
- Ovarian effects: Insulin synergises with LH to stimulate theca cell androgen production. The ovary does NOT become insulin-resistant — it remains exquisitely sensitive to insulin's steroidogenic effects. So while muscles and liver resist insulin (leading to hyperglycaemia), the ovary responds to high insulin levels by making even more androgens.
- Hepatic effects: Insulin suppresses SHBG synthesis by the liver → ↑free testosterone → more clinical hyperandrogenism (hirsutism, acne).
- Adrenal effects: Insulin potentiates ACTH-stimulated adrenal androgen production.
- Metabolic consequences: Compensatory hyperinsulinaemia → eventual β-cell exhaustion → impaired glucose tolerance → T2DM. This is why PCOS is a major risk factor for T2DM and is considered part of the metabolic syndrome [3][5].
- AMH is produced by granulosa cells of small antral follicles.
- In PMOS/PCOS, because there are many arrested small antral follicles, serum AMH is elevated (often 2–4× normal).
- AMH itself inhibits FSH-dependent follicle growth and aromatase expression → further contributing to follicular arrest and anovulation.
- The 2023 International Guideline allows AMH as an alternative to ultrasound for PCOM in adults only. Do not use AMH for diagnosis in adolescents because thresholds are not sufficiently standardised in that population.
- PCOS is associated with elevated inflammatory markers (CRP, IL-6, TNF-α).
- Inflammation contributes to insulin resistance and endothelial dysfunction.
- Visceral adipose tissue is a major source of pro-inflammatory cytokines.
The beauty (and frustration) of PCOS pathophysiology is that it is a self-reinforcing loop:
- Insulin resistance → hyperinsulinaemia → ↑ovarian androgen production + ↓SHBG.
- Hyperandrogenism → follicular arrest → anovulation.
- Anovulation → no progesterone → altered GnRH pulsatility → ↑LH:FSH ratio.
- ↑LH → more androgen production → more hyperandrogenism.
- Excess androgens → peripheral aromatisation to oestrone (a weak oestrogen) → chronic unopposed oestrogen → endometrial hyperplasia risk + altered HPO feedback.
- Obesity worsens insulin resistance → amplifies the entire cycle.
This is why weight loss (even 5–10%) can break the cycle — it reduces insulin resistance, lowers insulin levels, reduces androgen production, and can restore ovulation [1].
6. Classification
Based on the three Rotterdam criteria, four phenotypes are recognised:
| Phenotype | Hyperandrogenism (HA) | Oligo-anovulation (OA) | Polycystic Ovarian Morphology (PCOM) | Metabolic Risk |
|---|---|---|---|---|
| A ("Classic/Full-blown") | ✓ | ✓ | ✓ | Highest |
| B ("Classic without PCOM") | ✓ | ✓ | ✗ | High |
| C ("Ovulatory PCOS") | ✓ | ✗ | ✓ | Moderate |
| D ("Non-hyperandrogenic") | ✗ | ✓ | ✓ | Lowest |
Phenotype D Controversy
Phenotype D (non-hyperandrogenic) is the mildest form and was not recognised under the original NIH 1990 criteria. Some experts argue it may not truly represent PCOS. For exams, know that the metabolic and cardiovascular risk is greatest in phenotypes A and B (the "classic" forms with hyperandrogenism).
- NIH 1990 criteria: Required both hyperandrogenism AND oligo-anovulation (essentially phenotypes A + B only).
- AE-PCOS Society (2006): Required hyperandrogenism plus either oligo-anovulation or PCOM (phenotypes A, B, C).
- 2023 International Guideline: Reaffirmed the adult 2-of-3 diagnostic framework, allowed AMH as an alternative to ultrasound in adults only, and strengthened recognition of metabolic, cardiovascular, sleep, psychological, and pregnancy risks.
- 2026 global name consensus: Renamed PCOS to polyendocrine metabolic ovarian syndrome (PMOS), with a managed transition and planned integration into the 2028 International Guideline update.
7. Clinical Features
| Symptom | Pathophysiological Basis |
|---|---|
| Oligo/amenorrhoea (irregular, infrequent periods) [1][2] | Chronic anovulation → no corpus luteum → no progesterone-driven secretory endometrium → no regular withdrawal bleed. Cycles are often > 35 days (oligomenorrhoea) or absent for ≥ 6 months (secondary amenorrhoea). |
| Dysfunctional uterine bleeding / heavy menstrual bleeding | Chronic anovulation → continuous oestrogen stimulation (from peripheral aromatisation of androgens to oestrone) without progesterone opposition → endometrium proliferates excessively → unstable, thickened endometrium → irregular, sometimes heavy breakthrough bleeding. |
| Hirsutism (excess terminal hair in male-pattern distribution) [1] | Hyperandrogenism → androgens (especially testosterone and its more potent metabolite DHT via 5α-reductase) stimulate vellus hair follicles to transform into coarse terminal hairs in androgen-sensitive areas (upper lip, chin, chest, linea alba, inner thighs, back). Scored using the modified Ferriman-Gallwey score (≥ 4–6 considered significant, varies by ethnicity — lower threshold in East Asians). |
| Acne | Androgens → ↑sebum production [6] by pilosebaceous units → follicular hyperkeratinisation → microcomedo formation → Cutibacterium acnes proliferation → inflammatory acne. Often occurs in association with hyperandrogenic states, e.g., PCOS, virilisation tumours [6]. |
| Androgenic alopecia (female-pattern hair loss) | Excess androgens (DHT) → miniaturisation of scalp hair follicles, especially at the crown and frontal regions. Unlike male-pattern baldness, the frontal hairline is usually preserved in women. |
| Infertility [2][4] | Anovulation → no oocyte release → failure to conceive. PCOS accounts for ~80% of anovulatory infertility. Even when ovulation occurs, the quality of oocytes and endometrial receptivity may be suboptimal. |
| Weight gain / difficulty losing weight | Insulin resistance → hyperinsulinaemia promotes lipogenesis and inhibits lipolysis → favours weight gain, especially central/visceral adiposity. Obesity then worsens insulin resistance (vicious cycle). |
| Symptoms of insulin resistance | Fatigue, sugar cravings, postprandial somnolence — all due to impaired glucose utilisation by peripheral tissues despite high circulating insulin. |
| Psychological symptoms (anxiety, depression, low self-esteem) | Multifactorial: cosmetic burden of hirsutism/acne/obesity, infertility distress, hormonal imbalance (androgens may directly affect mood), and chronic disease burden. Prevalence of depression/anxiety is significantly higher in PCOS (up to 40%). |
| Obstructive sleep apnoea symptoms (snoring, daytime somnolence) | Obesity + possibly androgen-mediated effects on upper airway musculature → ↑OSA risk. Prevalence of OSA in PCOS is 5–30×higher than age-matched controls. |
| Sign | Pathophysiological Basis |
|---|---|
| Hirsutism (on examination) | As above — terminal hair in androgen-dependent areas. Assess with modified Ferriman-Gallwey score across 9 body areas. |
| Acne (face, chest, back) | As above — sebaceous gland hyperactivity due to hyperandrogenism. Distribution: typically affects areas with largest, hormone-responsive sebaceous glands, e.g., face, neck, chest, upper back, upper arms [6]. |
| Androgenic alopecia | Thinning at the crown with preservation of frontal hairline (Ludwig pattern in women). |
| Acanthosis nigricans | Velvety, hyperpigmented, thickened skin typically found in intertriginous areas (neck, axillae, groin, inframammary folds). Pathophysiology: hyperinsulinaemia → insulin binds IGF-1 receptors on keratinocytes and fibroblasts → stimulates epidermal and dermal proliferation → thickened, darkened skin. It is a cutaneous marker of insulin resistance, not of hyperandrogenism per se. |
| Obesity / central adiposity | ~50–70% of PCOS patients; characteristically truncal/central distribution. WHR (waist-to-hip ratio) is increased. In Hong Kong, BMI ≥ 23 is overweight; ≥ 25 is obese by Asian criteria. |
| Skin tags (acrochordons) | Another marker of insulin resistance / hyperinsulinaemia → IGF-1-mediated fibroblast proliferation. |
| Enlarged, smooth ovaries (on bimanual examination) | Bilateral ovarian enlargement due to multiple arrested follicles and stromal hypertrophy. Often not palpable clinically — ultrasound is needed. |
| Signs of virilisation (if present → suspect androgen-secreting tumour) | Deepening of voice, clitoromegaly, frontal balding, ↑muscle mass — these are NOT typical of PCOS (which causes mild-moderate hyperandrogenism). If virilisation is present, suspect an androgen-secreting tumour (ovarian or adrenal) or severe congenital adrenal hyperplasia. This is a crucial red flag. |
PCOS vs. Virilisation
PCOS causes hirsutism, acne, and mild androgenic alopecia — these are signs of mild-to-moderate hyperandrogenism. Virilisation (clitoromegaly, voice deepening, male-pattern baldness, increased muscle mass) suggests severe hyperandrogenism and should prompt investigation for androgen-secreting tumours or congenital adrenal hyperplasia, NOT PCOS. Don't confuse the two.
| Association | Mechanism |
|---|---|
| Metabolic syndrome (HTN, dyslipidaemia, insulin resistance, T2DM) [3][5] | Insulin resistance → metabolic syndrome: obesity, HT, HL, PCOS, NAFLD [3]. PCOS is both a cause and consequence of metabolic syndrome. ↑LDL-C, ↑TG, ↓HDL-C are typical. 30–40% of PCOS women have IGT by age 30; up to 10% have frank T2DM. |
| Non-alcoholic fatty liver disease (NAFLD) [3][5][7] | Considered the hepatic manifestation of metabolic syndrome [7]. Insulin resistance → ↑hepatic FFA flux → hepatic steatosis. PCOS women have 2–3× higher prevalence of NAFLD. |
| Endometrial hyperplasia / endometrial carcinoma | Chronic anovulation → unopposed oestrogen (from peripheral aromatisation of excess androgens to oestrone in adipose tissue) → continuous endometrial proliferation without progesterone-induced shedding → ↑risk of hyperplasia → potential progression to endometrial carcinoma (Type I, oestrogen-dependent). Risk is 2–6× higher. |
| Cardiovascular disease risk | Clustering of risk factors: insulin resistance, dyslipidaemia, obesity, chronic inflammation, endothelial dysfunction. Whether PCOS is an independent CVD risk factor beyond these conventional risk factors is still debated. |
| Gestational complications (when pregnancy is achieved) | ↑risk of gestational diabetes (3×), pre-eclampsia (3–4×), preterm birth, macrosomia, and Caesarean section — related to underlying insulin resistance and metabolic dysfunction. |
| Obstructive sleep apnoea [5] | Obesity + androgen effects on upper airway → ↑ collapsibility. |
| Psychological morbidity | Depression (28–64%), anxiety (34–57%), eating disorders, reduced quality of life. |
| Breast cancer risk | Mildly elevated (controversial) — chronic oestrogen exposure. Most studies show the risk increase is modest and may be confounded by obesity. |
8. Clinical Approach to PCOS (Pre-Diagnosis Framework)
When you see a young woman presenting with irregular periods, hirsutism, acne, weight gain, or infertility, think systematically:
- Menstrual history: Age of menarche, cycle length, regularity, duration and amount of bleeding, last menstrual period.
- Hyperandrogenic symptoms: Onset, duration, and progression of hirsutism, acne, hair loss. Rapid onset or virilisation → red flag for tumour.
- Fertility history: Duration of trying to conceive, previous pregnancies, partner assessment.
- Metabolic symptoms: Weight trajectory, distribution of weight gain, symptoms of diabetes, sleep quality.
- Psychological impact: Mood, self-esteem, body image, relationship impact.
- Family history (PCOS, T2DM, CVD, obesity).
- Weight history, diet, exercise.
- Drug history (e.g., valproate can cause PCOS-like features; exogenous androgens).
- BMI, waist circumference, blood pressure.
- Skin: hirsutism (Ferriman-Gallwey score), acne, acanthosis nigricans, skin tags, alopecia.
- Abdominal/pelvic examination: assess for ovarian enlargement (bimanual), virilisation signs.
- Thyroid examination (to exclude thyroid disease as cause of menstrual irregularity).
This will be covered in detail in the next section, but the key conditions to exclude are:
- Hormonal profile, imaging, metabolic workup — to be detailed in the diagnostic section.
- Lean PCOS is proportionally more common in East Asian populations. Even with BMI < 23, significant insulin resistance and hyperandrogenism can be present. Don't be falsely reassured by a normal BMI.
- Dietary factors: Increasing consumption of high-glycaemic-index foods and westernised diets in Hong Kong contribute to worsening metabolic profiles.
- Ethnic variation in hirsutism: East Asian women generally have less body hair than Caucasian or South Asian women. Therefore, even mild hirsutism (modified Ferriman-Gallwey score ≥ 4) should raise suspicion for hyperandrogenism in Chinese women.
- Cultural factors: Infertility carries significant psychosocial burden in Chinese families, which may drive earlier presentation to fertility clinics. Conversely, menstrual irregularity may be normalised or attributed to Traditional Chinese Medicine concepts (e.g., "blood deficiency"), leading to delayed diagnosis.
High Yield Summary
Definition: PMOS, formerly PCOS, is a heterogeneous endocrine-metabolic disorder diagnosed by the current adult guideline criteria — 2 out of 3: (1) oligo-anovulation, (2) clinical/biochemical hyperandrogenism, (3) PCOM on ultrasound (FNPO > 20 and/or ovarian volume ≥ 10 mL) or elevated AMH in adults — after excluding other causes.
Epidemiology: Most common endocrine disorder in reproductive-age women (5–15%); leading cause of anovulatory infertility (~80%).
Core Pathophysiology (the vicious cycle):
- Hyperandrogenism — intrinsic theca cell dysfunction + LH excess + insulin-driven augmentation.
- Insulin resistance + hyperinsulinaemia — ↑ovarian androgens, ↓SHBG, metabolic syndrome.
- Abnormal GnRH pulsatility — ↑LH:FSH ratio → ↑androgens + follicular arrest.
- Anovulation — no dominant follicle → no progesterone → no cycle regulation → unopposed oestrogen.
Key Clinical Features:
- Symptoms: Oligo/amenorrhoea, hirsutism, acne, androgenic alopecia, infertility, weight gain, psychological distress.
- Signs: Hirsutism (Ferriman-Gallwey), acne, acanthosis nigricans, central obesity, skin tags.
- Red flags for tumour: Rapid-onset virilisation (clitoromegaly, voice deepening).
Long-term Associations: T2DM, metabolic syndrome, NAFLD, endometrial hyperplasia/carcinoma, CVD risk, OSA, psychological morbidity, gestational complications.
Management pillars (from lecture slides): Weight reduction; menstrual regulation (prevent endometrial hyperplasia/CA) with periodic progestogen or COC pills; hirsutism management with COC pills, cosmetic measures, anti-oestrogens; fertility via ovulation induction by letrozole / gonadotrophin; long-term metabolic disorder surveillance. [1]
Active Recall - PCOS: Definition, Epidemiology, Pathophysiology, and Clinical Features
[1] Lecture slides: GC 114. Climacteric symptoms menopause and related illness; amenorrhoea.pdf (p14, p28) [2] Lecture slides: GC 117. I want to have a baby male and female infertility.pdf (p32) [3] Senior notes: Ryan Ho Endocrine.pdf (p77, p117) [4] Lecture slides: Block C - I want to have a baby_ male and female infertility.pdf (p11) [5] Senior notes: Maksim Medicine Notes.pdf (p79–80) [6] Senior notes: Ryan Ho Rheumatology.pdf (p126 — Acne Vulgaris) [7] Senior notes: Ryan Ho GI.pdf (p309 — NAFLD) [8] Teede HJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Fertility and Sterility. 2023. [9] Teede HJ, et al. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. Lancet. 2026. [10] Endocrine Society. Polyendocrine Metabolic Ovarian Syndrome: New name to improve diagnosis and care. 2026.
Differential Diagnosis of PMOS (formerly PCOS)
PMOS/PCOS is a diagnosis of exclusion. Before you can confidently label someone with PMOS/PCOS, you must systematically rule out other conditions that can mimic one or more diagnostic criteria (oligo-anovulation, hyperandrogenism, and PCOM/elevated AMH in adults). Think of it this way: PMOS/PCOS sits at the intersection of menstrual irregularity, hyperandrogenism, and metabolic dysfunction — and plenty of other conditions can produce these features.
The differential diagnosis is best approached by considering which presenting feature you are evaluating.
The Rotterdam criteria are phenotypic — they describe what you see, not the underlying cause. Many conditions can produce:
- Oligo/amenorrhoea (any disruption of the HPO axis)
- Hyperandrogenism (any excess androgen source — ovarian, adrenal, exogenous, or peripheral)
- Polycystic ovarian morphology (can be an incidental finding in up to 20–30% of normal women)
Therefore, the diagnostic approach requires you to exclude mimics before applying the Rotterdam label. This is not just academic — missing congenital adrenal hyperplasia or an androgen-secreting tumour has serious consequences.
Systematic Differential Diagnosis
| Condition | Key Distinguishing Features | Why It Mimics PMOS/PCOS |
|---|---|---|
| Congenital adrenal hyperplasia (CAH) — non-classic/late-onset [5][8][9] | Elevated 17-hydroxyprogesterone (17-OHP) [9]; autosomal recessive; may present with primary or secondary amenorrhoea, hirsutism, acne; 21-hydroxylase deficiency is commonest | Adrenal androgen excess from impaired cortisol synthesis → ↑ACTH → adrenal hyperplasia → shunting of steroid precursors into androgen pathway. Can cause oligo-anovulation + hyperandrogenism + even polycystic ovarian morphology. The single most important differential to exclude — prevalence ~1–5% of hyperandrogenic women. |
| Androgen-secreting tumours (ovarian: Sertoli-Leydig cell, hilus cell; adrenal: carcinoma, adenoma) [5][8] | Rapid onset (weeks to months) of virilisation (clitoromegaly, voice deepening, male-pattern baldness, ↑muscle mass); markedly elevated testosterone (typically > 5 nmol/L or > 150 ng/dL); adrenal tumours also have ↑DHEA-S | Tumour autonomously secretes large quantities of androgens. Unlike PMOS/PCOS, which causes mild-moderate hyperandrogenism over years, tumours produce severe, rapidly progressive virilisation. |
| Cushing's syndrome [2][5][8][10] | Truncal obesity, moon face, buffalo hump, purplish striae, thin skin, easy bruising, proximal myopathy [10]; HTN, hyperglycaemia; oligo/amenorrhoea due to cortisol-mediated GnRH suppression; hirsutism, acne (↑ACTH → ↑androgen) [10] | Excess cortisol from any cause → ↑adrenal androgens (ACTH-dependent forms) + metabolic syndrome features. The overlap with PCOS can be significant (central obesity, menstrual irregularity, hirsutism, insulin resistance). Screen with overnight 1mg dexamethasone suppression test [10][11]. |
| Hyperprolactinaemia [2][5][8][12] | Galactorrhoea, headache, visual field defects (if macroadenoma); amenorrhoea/oligomenorrhoea; may have mild hyperandrogenism | Elevated prolactin → suppresses GnRH pulsatility → ↓LH/FSH → oligo-anovulation → secondary amenorrhoea. Mild androgen excess can occur because ↓FSH → ↓aromatase → ↓conversion of androgens to oestrogens. Also, prolactin may directly stimulate adrenal DHEA-S production. Check serum prolactin. |
| Acromegaly [13] | Coarsening of facial features, prognathism, large hands/feet, ↑shoe/glove size, headache, visual field defects, skin thickening, hirsutism (56%) [13], sweating, OSA | GH excess → IGF-1 mediated effects on hair follicles and sebaceous glands → hirsutism and skin changes. Also causes insulin resistance → metabolic syndrome features resembling PCOS. Amenorrhoea can occur due to pituitary mass effect or co-secretion of prolactin. |
| Drug-induced hyperandrogenism [8] | History of anabolic steroids, testosterone, DHEA supplements, danazol, valproic acid (increases androgen levels and can cause PCOM) | Exogenous androgens or drugs that alter steroidogenesis directly cause hyperandrogenic features. Valproic acid is particularly important — it causes weight gain, insulin resistance, and PCOS-like features in women with epilepsy. |
| Idiopathic hirsutism | Hirsutism with normal androgens, regular ovulatory cycles, normal ovarian morphology | Increased peripheral 5α-reductase activity in skin → enhanced conversion of testosterone to the more potent DHT → hirsutism without systemic androgen excess. By definition, this is NOT PCOS (no oligo-anovulation, no biochemical hyperandrogenism). |
The differential diagnosis of secondary amenorrhoea [5]:
| Category | Conditions | Key Features / Why It's in the DDx |
|---|---|---|
| Physiological [5] | Pregnancy, menopause, lactation | Always exclude pregnancy first — the most common cause of secondary amenorrhoea in reproductive-age women. Don't forget the PHYSIOLOGICAL causes e.g. pregnancy! [12]. Lactational amenorrhoea is due to prolactin-mediated GnRH suppression. |
| Hypothalamic [5][2] | Functional hypothalamic amenorrhoea (FHA) (weight change: obesity, anorexia nervosa; psychological disturbance; excessive exercise) [2]; Kallmann syndrome (GnRH deficiency); brain lesions [5] | FHA: Chronic energy deficit or stress → ↓GnRH pulsatility → ↓LH/FSH → anovulation. Distinguishing from PCOS: FHA patients typically have low LH, FSH, and oestradiol (hypogonadotropic hypogonadism), while PCOS patients have normal-to-high LH with normal-to-low FSH. FHA patients are often underweight or have history of restrictive eating/intense exercise. |
| Pituitary [5][2] | Hyperprolactinaemia; Sheehan's syndrome (postpartum pituitary necrosis); pituitary adenomas; empty sella [5][2] | See hyperprolactinaemia above. Sheehan's syndrome [2]: postpartum haemorrhage → pituitary infarction → hypopituitarism → amenorrhoea + failure of lactation. Clue: history of severe PPH. |
| Ovarian [5][2] | Premature ovarian insufficiency (POI) (chromosomal disorders e.g. Turner syndrome, surgery, radiotherapy, chemotherapy, mumps, autoimmune) [2][5][12] | POI: Depletion or dysfunction of ovarian follicles before age 40. Key distinguishing feature: FSH > 25 IU/L × twice (≥ 4 weeks apart) [12] — this is hypergonadotropic hypogonadism (elevated FSH because the ovary is failing, so no negative feedback). PCOS has normal-to-low FSH. |
| Thyroid disorders [2][8][12] | Hypothyroidism, hyperthyroidism | Hypothyroidism → ↑TRH → ↑prolactin → GnRH suppression → amenorrhoea. Also, hypothyroidism → ↓SHBG → ↑free androgens → may mimic mild hyperandrogenism. Hyperthyroidism → ↑SHBG → altered gonadotropin dynamics. Always check TFT. |
| Anatomic [5] | Asherman's syndrome (extensive intrauterine adhesions due to instrumentation); MRKH syndrome (Müllerian duct agenesis) [5]; outflow tract obstruction [12] | Asherman's: Post-curettage intrauterine adhesions → mechanical obstruction to menstrual flow → amenorrhoea despite normal HPO axis function. The ovaries are cycling normally. Clue: history of uterine instrumentation (D&C, especially post-pregnancy). |
| Condition | Explanation |
|---|---|
| Normal variant PCOM | Up to 20–30% of young women in the general population have polycystic ovarian morphology on ultrasound without meeting PCOS criteria. This is especially common in adolescents. PCOM alone is NOT sufficient for diagnosis. |
| Hypothalamic amenorrhoea | Prolonged anovulation from any cause can lead to accumulation of small antral follicles → PCOM-like appearance. The underlying hormonal milieu is different (low gonadotropins in FHA vs. elevated LH in PCOS). |
| Hypothyroidism | Can cause ovarian enlargement with multicystic appearance due to elevated TSH cross-reacting with FSH receptors (rare, but documented). |
| CAH | As above — can cause PCOM secondary to hyperandrogenism disrupting follicular development. |
The following mermaid diagram illustrates the systematic approach to differentiating PCOS from its mimics:
| Feature | PMOS/PCOS | Non-classic CAH | FHA | POI | Cushing's | Androgen-secreting tumour |
|---|---|---|---|---|---|---|
| Onset | Peri-menarchal, gradual | Peri-menarchal or later | Associated with stress/weight loss/exercise | Variable (< 40y) | Gradual (months-years) | Rapid (weeks-months) |
| BMI | Often ↑ (but can be lean) | Variable | Often ↓ or normal | Variable | Central obesity | Variable |
| Virilisation | No (mild-moderate HA only) | Rarely | No | No | Rarely | Yes — key red flag |
| LH:FSH | ↑LH:FSH (often > 2:1) | Variable | Both low | ↑↑FSH | Variable | Variable |
| Testosterone | Mildly ↑ | Mildly ↑ | Normal/low | Normal/low | Mildly ↑ | Markedly ↑ (> 5 nmol/L) |
| 17-OHP | Normal | Elevated | Normal | Normal | Normal | Normal |
| DHEA-S | Normal/mildly ↑ | Mildly ↑ | Normal | Normal | ↑ | ↑↑ (if adrenal source) |
| Cortisol | Normal | Normal | Normal/low | Normal | Elevated (fails to suppress) | Normal |
| FSH | Normal-low | Normal | Low | > 25 IU/L | Normal | Normal |
| Prolactin | Normal | Normal | Normal/mildly ↑ | Normal | Normal | Normal |
| PCOM on USS | Present (≥ 2/3 criteria) | May be present | May be present | Small/atrophic ovaries | Not typical | Unilateral mass |
Before diagnosing PMOS/PCOS, you must perform the following baseline investigations (this is essentially your "exclusion checklist"):
- βhCG — exclude pregnancy
- TSH — exclude thyroid disorders [2][8][12]
- Serum prolactin — exclude hyperprolactinaemia [2][5][8][12]
- 17-hydroxyprogesterone (17-OHP) — exclude congenital adrenal hyperplasia [8][9][12]
- Total testosterone ± DHEA-S — if markedly elevated, investigate for androgen-secreting tumour [5][8]
- FSH (± LH, oestradiol) — distinguish PCOS (normal-low FSH) from premature ovarian insufficiency (FSH > 25 IU/L) [12] and hypothalamic amenorrhoea (low FSH, low LH)
- Consider overnight 1mg DST or 24h UFC — if clinical features suggest Cushing's syndrome [10][11]
Exam Trap
A common exam mistake is to diagnose PMOS/PCOS without excluding other causes. Remember: PMOS/PCOS is a diagnosis of EXCLUSION. You cannot apply the diagnostic criteria until you have checked at minimum: βhCG, TSH, prolactin, and 17-OHP. If there is any suspicion of Cushing's or tumour, additional workup is mandatory. The question stem may deliberately include a subtle clue pointing to CAH or Cushing's — don't miss it.
Rapid Virilisation = NOT PMOS/PCOS
If a woman presents with rapidly progressive deepening of voice, clitoromegaly, temporal balding, or markedly elevated testosterone (> 5 nmol/L / > 150 ng/dL), this is virilisation and suggests an androgen-secreting tumour, not PMOS/PCOS. PMOS/PCOS produces mild-moderate hyperandrogenism over years. Speed of onset and severity of virilisation are the key discriminators.
High Yield Summary
PMOS/PCOS is a diagnosis of exclusion. Before applying the diagnostic criteria, you must rule out:
- Pregnancy (βhCG)
- Thyroid disorders (TSH) [2][12]
- Hyperprolactinaemia (prolactin) [2][5][12]
- Non-classic CAH (17-OHP — the most important mimic) [8][9][12]
- Cushing's syndrome (overnight DST if clinically suspected) [10][11]
- Androgen-secreting tumour (if testosterone markedly ↑ or rapid virilisation) [5][8]
- Premature ovarian insufficiency (FSH > 25 IU/L × 2) [12]
- Functional hypothalamic amenorrhoea (low LH, FSH, E2 — associated with underweight/stress/excessive exercise) [2][5]
Key discriminators:
- LH:FSH ratio > 2:1 favours PMOS/PCOS
- FSH > 25 favours POI
- Low LH + low FSH + low E2 favours hypothalamic cause
- Elevated 17-OHP favours non-classic CAH
- Rapid virilisation + testosterone > 5 nmol/L favours tumour
- Failed cortisol suppression favours Cushing's
Active Recall - Differential Diagnosis of PCOS
References
[2] Lecture slides: GC 117. I want to have a baby male and female infertility.pdf (p32) [5] Senior notes: Maksim Medicine Notes.pdf (p79, p103) [8] Senior notes: Maksim Medicine Notes.pdf (p103 — Hyperandrogenism aetiology) [9] Senior notes: Ryan Ho Endocrine.pdf (p74 — Congenital Adrenal Hyperplasia) [10] Senior notes: Maksim Medicine Notes.pdf (p99 — Cushing's syndrome) [11] Senior notes: Ryan Ho Chemical Path.pdf (p29 — Diagnosis of Cushing Syndrome) [12] Lecture slides: Block C - Climacteric symptoms_ menopause and related illness; amenorrhoea.pdf (p9, p14, p15) [13] Senior notes: Ryan Ho Endocrine.pdf (p111 — Acromegaly)
Diagnostic Criteria, Algorithm, and Investigations for PMOS (formerly PCOS)
1. Diagnostic Criteria
PMOS, formerly PCOS, remains a phenotypic diagnosis of exclusion. In adults, the 2023 International Guideline keeps the familiar 2 out of 3 framework, after exclusion of other aetiologies [1][12][17]:
Two out of the three criteria (Rotterdam consensus):
Let's dissect each criterion from first principles so you understand exactly what you're looking for and why.
What counts?
- Oligomenorrhoea: Cycle length > 35 days (i.e., < 9 cycles per year). Some definitions use > 6 weeks [5].
- Amenorrhoea: Absence of menses for ≥ 3 months in a woman with previously regular cycles, or ≥ 6 months if previously irregular.
- Anovulation with regular cycles: Less common, but some women with PCOS have cycles that appear regular (25–35 days) yet are anovulatory. Confirmed by low mid-luteal progesterone (see below).
Why does this happen in PCOS? Recall the pathophysiology: ↑GnRH pulse frequency → ↑LH, ↓FSH → insufficient FSH to drive a dominant follicle to maturity → follicular arrest → no ovulation → no corpus luteum → no progesterone → no organised secretory-phase endometrium → no regular withdrawal bleed.
How to assess:
- Clinical history: Menstrual calendar/diary — the simplest and most important tool.
- Serum mid-luteal progesterone levels (a week before next expected period) [14]: Progesterone > 16 nmol/L (> 5 ng/mL) confirms ovulation occurred. If low → anovulatory cycle.
- Why mid-luteal? Because progesterone peaks 7 days after ovulation (i.e., day 21 in a 28-day cycle). If cycles are irregular, you estimate: expected period date minus 7 days.
- For irregular cycles: FSH, prolactin, thyroxine [14] — to investigate the cause of anovulation.
- For regular cycles: prolactin or thyroxine not indicated [14] — the focus is on confirming ovulation with mid-luteal progesterone.
Adolescent Caveat
In adolescents, physiological oligo-anovulation is common as the HPO axis matures. The 2023 International Guideline recommends caution in diagnosing PMOS/PCOS in adolescents — both hyperandrogenism AND persistent ovulatory dysfunction should be present. Ultrasound criteria for PCOM and AMH should NOT be used in adolescents due to high prevalence of multifollicular ovaries and immature AMH thresholds as normal developmental variants.
Clinical hyperandrogenism — any one of:
- Hirsutism: Excess terminal hair in androgen-dependent areas. Assessed by the modified Ferriman-Gallwey (mFG) score across 9 body areas (upper lip, chin, chest, upper back, lower back, upper abdomen, lower abdomen, upper arms, thighs). Score ≥ 4–6 is significant (ethnicity-dependent — use lower threshold ≥ 4 for East Asian women).
- Acne: Moderate-severe acne, especially if persistent beyond adolescence or resistant to standard treatment.
- Androgenic alopecia: Female-pattern hair loss (Ludwig pattern — diffuse thinning at crown with preserved frontal hairline).
Biochemical hyperandrogenism — elevated androgens on blood tests:
- Total testosterone: The most commonly measured. Mildly elevated in PCOS (typically 1.5–5 nmol/L).
- Free testosterone (calculated or measured): More sensitive than total testosterone because SHBG is often suppressed in PCOS (due to hyperinsulinaemia), meaning total testosterone may be "normal" while free testosterone is elevated.
- SHBG: Low in PCOS due to insulin-mediated hepatic suppression. A low SHBG increases bioavailable testosterone.
- Free Androgen Index (FAI): = (Total testosterone / SHBG) × 100. A calculated surrogate for free testosterone. Elevated FAI is a sensitive marker.
- DHEA-S: Mildly elevated in ~50% of PCOS (adrenal contribution). Markedly elevated DHEA-S (> 18.9 µmol/L) suggests adrenal tumour.
- Androstenedione: May be elevated; less commonly measured.
Why both clinical AND biochemical? Because some women have clear hirsutism or acne but normal blood androgens (due to ↑peripheral 5α-reductase activity or ethnic variation), while others have elevated androgens but minimal clinical signs (ethnic variation in hair follicle sensitivity). Either alone satisfies this criterion.
Polycystic ovarian morphology on ultrasound [1][12]:
- Follicle number per ovary (FNPO) of > 20 — using modern transvaginal ultrasound probes (≥ 8 MHz). The original 2003 threshold was > 12, but with improved ultrasound resolution, more follicles are detected in normal women, so international guidance raised the threshold to > 20.
- and/or an ovarian volume ≥ 10 mL — calculated by the prolate ellipsoid formula: 0.5 × length × width × depth.
What are you seeing? Multiple small antral follicles (2–9 mm), often arranged peripherally in a "string of pearls" pattern, with echogenic (bright) central stroma due to stromal hyperthecosis. These are NOT true cysts — they are arrested follicles that failed to achieve dominance.
Important caveats:
- Only one ovary needs to meet the criteria.
- Transvaginal USS is the gold standard. If transvaginal is not possible (e.g., in adolescents or virgo intacta), transabdominal USS can be used, but ovarian volume ≥ 10 mL should be used (follicle count is unreliable transabdominally).
- Do NOT use PCOM as a criterion in adolescents < 8 years post-menarche — multifollicular ovaries are a normal developmental finding.
- Timing: Ideally in the early follicular phase (days 3–5) to avoid confusion with a dominant follicle or corpus luteum.
- If on COC pills: Ultrasound morphology is altered (COCs suppress follicle development); PCOM assessment should ideally be done ≥ 3 months after stopping COCs.
Anti-Müllerian Hormone (AMH) as an alternative: The 2023 International Guideline allows serum AMH as an alternative to ultrasound for PCOM in adults (not adolescents). AMH is produced by granulosa cells of small antral follicles — elevated AMH reflects the increased follicle count, but thresholds remain assay- and population-specific. AMH has the advantages of being:
- Not affected by the day of the cycle.
- Not operator-dependent.
- Useful when USS is not possible.
However, AMH should not be used as a stand-alone diagnostic test, should not be used in adolescents, and should not be combined with ultrasound simply to "double count" the same PCOM criterion. Assay standardisation is still evolving, so interpret local thresholds carefully.
| Feature | NIH 1990 | Rotterdam 2003 | AE-PCOS Society 2006 | 2023 International Guideline |
|---|---|---|---|---|
| Hyperandrogenism | Required | 2 of 3 | Required | 2 of 3 in adults |
| Oligo-anovulation | Required | 2 of 3 | Either OA or PCOM | 2 of 3 |
| PCOM on USS | Not included | 2 of 3 | Either OA or PCOM | 2 of 3; FNPO > 20 and/or ovarian volume ≥ 10 mL |
| Exclusion of other causes | Yes | Yes | Yes | Yes |
| AMH as alternative to USS | No | No | No | Yes, adults only |
| Adolescent modifications | No | No | No | Yes — require HA + persistent ovulatory dysfunction; avoid USS/AMH |
For Exams: Use Rotterdam
The Rotterdam-style 2-of-3 framework is what is taught in the HKUMed lecture slides [1][12] and remains the international adult framework. For exam purposes during the name transition, state: "PMOS/PCOS is diagnosed by 2 out of 3 criteria after exclusion of other aetiologies; AMH can substitute for ultrasound in adults only."
The diagnostic workup for PCOS has two goals:
- Exclude mimics (the conditions from the DDx section)
- Confirm ≥ 2 of 3 adult diagnostic criteria
And then a third step: 3. Screen for metabolic complications (because PCOS is not just a reproductive disorder — it's a metabolic one)
Step-by-Step Algorithm
3. Investigation Modalities: Detailed Interpretation
I'll now walk through every investigation systematically, explaining what you're measuring, why, expected findings in PCOS, and how to interpret abnormalities.
Amenorrhoea — Evaluation: Investigations: FSH, LH, E2, PRL, TFT, testosterone [15][16]
| Investigation | What You're Measuring | Expected in PCOS | Why / Interpretation |
|---|---|---|---|
| βhCG | Human chorionic gonadotropin | Negative | Don't forget the PHYSIOLOGICAL causes e.g. pregnancy! [12]. Always the first test. |
| FSH | Follicle-stimulating hormone | Normal to low (typically 3–8 IU/L) | FSH is relatively suppressed because: (1) ↑GnRH pulse frequency favours LH over FSH, (2) chronic oestrogen exposure (from peripheral aromatisation of androgens) suppresses FSH, (3) elevated inhibin B from multiple small antral follicles suppresses FSH. High FSH ( > 25 IU/L) indicates ovarian insufficiency [2][4][14] — NOT PCOS. |
| LH | Luteinising hormone | Elevated (often > 10 IU/L) | ↑GnRH pulse frequency preferentially drives LH synthesis. LH excess stimulates theca cell androgen production. |
| LH:FSH ratio | Ratio of LH to FSH | > 2–2.5 [8] | A classic (though not universal) finding in PCOS. Present in ~60% of cases. The elevated ratio reflects the neuroendocrine dysregulation. However, a normal ratio does NOT exclude PCOS — it is supportive, not diagnostic. |
| Oestradiol (E2) | Serum oestradiol | Normal to mildly elevated | In PCOS, E2 is not low (unlike in POI or FHA) because: (1) there are many antral follicles producing some oestradiol, (2) peripheral aromatisation of excess androgens to oestrone (E1) in adipose tissue contributes to total oestrogen levels. Chronically "tonic" (non-cyclical) oestrogen without the mid-cycle surge. |
| Prolactin | Serum prolactin | Normal | To exclude hyperprolactinaemia [2][4][12][14][15][16]. Elevated prolactin → suggests prolactinoma or drug-related cause. Note: mild prolactin elevation (up to 1.5× ULN) can occur in PCOS itself (due to chronic oestrogen stimulation of lactotrophs), so marked elevation is more concerning. |
| TSH (± fT4) | Thyroid function | Normal | To exclude thyroid disorders [2][4][14][15][16]. Both hypothyroidism and hyperthyroidism can cause menstrual irregularity. Hypothyroidism also lowers SHBG → ↑free androgens, potentially mimicking PCOS. |
| Total testosterone | Main circulating androgen | Mildly elevated (typically 1.5–5 nmol/L) | Confirms biochemical hyperandrogenism. In PCOS, testosterone is mildly to moderately elevated. If > 5 nmol/L (> 150 ng/dL) → suspect androgen-secreting tumour [8]. Drawn fasting, in the morning (testosterone has diurnal variation — highest in the AM). |
| 17-OH progesterone (17-OHP) | Steroid precursor in cortisol synthesis pathway | Normal (< 6 nmol/L / < 200 ng/dL in early follicular phase) | To exclude congenital adrenal hyperplasia (non-classic 21-hydroxylase deficiency) [8][9][15][16]. In CAH, 21-hydroxylase deficiency blocks cortisol synthesis → 17-OHP accumulates → shunted into androgen pathway. If 17-OHP is elevated, confirm with ACTH (Synacthen) stimulation test: exaggerated 17-OHP response (> 30 nmol/L) confirms CAH. Best measured in the early follicular phase (days 3–5) in the morning. |
Other Investigations (depending on the cause): Androgens (SHBG, 17-OH progesterone), E+P withdrawal test, Dynamic tests: GnRH test for pituitary function [15][16]
| Investigation | When to Order | Expected in PCOS | Interpretation |
|---|---|---|---|
| SHBG | When total testosterone is borderline/normal but clinical hyperandrogenism is present | Low | Hyperinsulinaemia suppresses hepatic SHBG production → ↑free (bioavailable) testosterone. Low SHBG is itself a marker of insulin resistance. |
| Free Androgen Index (FAI) | Calculated: (Total testosterone / SHBG) × 100 | Elevated (> 5) | More sensitive than total testosterone for detecting biochemical hyperandrogenism because it accounts for low SHBG. |
| DHEA-S | If virilisation or markedly elevated testosterone — to localise androgen source | Normal or mildly elevated | DHEA-S is almost exclusively of adrenal origin. Mild elevation is common in PCOS (~50% of cases). Markedly elevated DHEA-S (> 18.9 µmol/L) suggests adrenal tumour or adrenal hyperplasia. |
| Androstenedione | Additional androgen assessment | May be elevated | Produced by both ovary and adrenal. Less commonly measured but can be elevated when testosterone is borderline. |
| Overnight 1mg dexamethasone suppression test (DST) [10][11] | If clinical features suggest Cushing's syndrome (central obesity, striae, bruising, myopathy, hyperglycaemia) | Normal (cortisol suppresses to < 50 nmol/L) | To exclude Cushing's syndrome [10][11][14]. In Cushing's, cortisol fails to suppress because the HPA axis is driven autonomously (by ACTH-secreting adenoma, ectopic ACTH, or adrenal tumour). |
| Progestogen challenge test [15][16] | To assess endogenous oestrogen status in amenorrhoeic women | Withdrawal bleed occurs → indicates adequate oestrogen and patent outflow tract | Give medroxyprogesterone acetate 10 mg/day for 5–10 days. If withdrawal bleeding occurs within 2–7 days of completing the course → confirms (1) the endometrium has been primed by oestrogen (i.e., oestrogen is present, ruling out severe hypo-oestrogenism), and (2) the outflow tract is patent (ruling out Asherman's). In PCOS, withdrawal bleeding typically occurs (because chronic anoestrone keeps the endometrium proliferated). |
| E+P withdrawal test [15][16] | If progestogen challenge test produces no bleeding — to distinguish outflow tract obstruction from hypo-oestrogenism | Bleeding after combined oestrogen + progesterone → confirms outflow tract is patent but oestrogen levels are very low (hypogonadism) | Give conjugated oestrogen (1.25 mg/day for 21 days) + medroxyprogesterone acetate (10 mg/day for last 5 days). If still no bleed → outflow tract problem (Asherman's, cervical stenosis). |
| GnRH stimulation test [15][16] | If hypogonadotropic hypogonadism — to distinguish hypothalamic from pituitary cause | Not typically needed in PCOS workup | IV GnRH bolus → measure LH and FSH response at 20 and 60 minutes. Exaggerated LH response in PCOS. No/blunted response → pituitary disease. Delayed response (better at 60 min) → hypothalamic cause. |
| Parameter | Criteria for PCOM | Interpretation |
|---|---|---|
| Follicle number per ovary (FNPO) | > 20 [1][12] (per ovary, using TVS with ≥ 8 MHz probe) | Count follicles 2–9 mm in both longitudinal and transverse planes. The original 2003 threshold was > 12, but modern guidance raised this to > 20 to account for improved ultrasound technology detecting more follicles. |
| Ovarian volume | ≥ 10 mL [1][12] | Calculated as 0.5 × length × width × depth (prolate ellipsoid formula). Enlarged ovaries reflect stromal hypertrophy (from chronic LH stimulation) + multiple arrested follicles. |
| Distribution pattern | Peripheral arrangement ("string of pearls") | Classic but not required for diagnosis. Follicles arranged along the ovarian cortex with echogenic (bright) central stroma. |
| Endometrial thickness | May be thickened | Chronic unopposed oestrogen → endometrial proliferation. If endometrium is > 12 mm in a non-pregnant, non-secretory phase, consider endometrial sampling to exclude hyperplasia. |
Practical points:
- Only one ovary needs to meet the PCOM criteria.
- Timing: Best in early follicular phase (days 3–5 of cycle, if menstruating) to avoid confusion with a dominant follicle or corpus luteum cyst.
- Transvaginal USS is the gold standard. Transabdominal USS can be used if TVS is not possible (e.g., virgin patients), but rely on ovarian volume rather than follicle count.
- On COC pills: Morphology is altered; ideally reassess ≥ 3 months after stopping.
- Exclude other ovarian pathology: Look for adnexal masses, solid components (→ tumour), dermoid cysts, endometriomas.
Radiological: 3D USG pelvis / MRI / USG renal tract; Pituitary imaging; Visual field by perimetry [15][16]
| Investigation | Indication | What You're Looking For |
|---|---|---|
| Pituitary imaging (MRI) [15][16] | Suspected pituitary cause — hyperprolactinaemia, visual symptoms, hypopituitarism | Pituitary adenoma (prolactinoma, non-functioning adenoma, Cushing's disease). Not needed routinely in PCOS workup unless prolactin is elevated or pituitary pathology is suspected. |
| Visual field perimetry [15][16] | If pituitary macroadenoma suspected | Bitemporal hemianopia from optic chiasm compression. |
| CT adrenals | Markedly elevated testosterone or DHEA-S → adrenal tumour | Adrenal mass. |
| MRI pelvis | Equivocal USS, suspected ovarian tumour, Müllerian anomaly | Better tissue characterisation than USS. |
| Laparoscopy / hysteroscopy [15][16] | Suspected outflow tract problem (Asherman's), endometriosis, tubal assessment in infertility | Direct visualisation of pelvic anatomy. Not part of routine PCOS workup. |
This is critical because PCOS is a metabolic disease as much as a reproductive one. The long-term morbidity is driven by metabolic complications.
| Investigation | What You're Screening For | Expected Findings in PCOS | Frequency |
|---|---|---|---|
| Oral Glucose Tolerance Test (OGTT) — 75g | Impaired glucose tolerance (IGT), T2DM | Fasting glucose ≥ 5.6 mmol/L = IFG; 2h glucose 7.8–11.0 = IGT; ≥ 11.1 = T2DM. OGTT is preferred over fasting glucose alone because many PCOS women have normal fasting glucose but abnormal 2h glucose (post-challenge hyperglycaemia due to insulin resistance). | At diagnosis, then every 1–3 years depending on risk |
| Fasting glucose + HbA1c | Diabetes screening | HbA1c ≥ 48 mmol/mol (6.5%) = T2DM. Can be used alongside OGTT. HbA1c alone may miss early IGT. | At diagnosis, then annually |
| Fasting lipid profile | Dyslipidaemia, i.e. ↑LDL-C, TG, ↓HDL-C [3] | Typical pattern: ↑triglycerides, ↓HDL-C, ↑LDL-C (or ↑small dense LDL). This atherogenic lipid profile is driven by insulin resistance. | At diagnosis, then every 1–2 years |
| Blood pressure | Hypertension | May be elevated — part of metabolic syndrome [3]. | Every visit |
| BMI + waist circumference | Obesity, central adiposity | BMI ≥ 23 overweight, ≥ 25 obese (Asian criteria). Waist circumference ≥ 80 cm in Asian women indicates central obesity. | Every visit |
| Liver function tests (LFT) | NAFLD [3][7] | May show mild ↑ALT/AST (typically < 2× ULN). If elevated, consider liver USS. | At diagnosis |
| Fasting insulin (± HOMA-IR) | Insulin resistance | Fasting insulin often > 60 pmol/L. HOMA-IR = (fasting glucose × fasting insulin) / 22.5. Values > 2.5 suggest insulin resistance. Note: fasting insulin is NOT routinely recommended in international guidance due to poor standardisation, but is used in some centres. | Not routine |
| Mood/depression screening | Psychological comorbidity | PHQ-9 or similar validated tool. Prevalence of depression 28–64% in PCOS. | At diagnosis, then periodically |
| OSA screening | Obstructive sleep apnoea | Epworth Sleepiness Scale. If symptomatic or BMI > 30 → refer for polysomnography. | If symptomatic |
Why OGTT Over Fasting Glucose?
In PMOS/PCOS, insulin resistance preferentially affects post-prandial glucose handling. Many women will have a normal fasting glucose but an abnormal 2-hour post-load glucose on OGTT. Using fasting glucose or HbA1c alone will miss up to 40% of women with IGT or T2DM. International guidance recommends OGTT as the preferred metabolic screening test in PMOS/PCOS.
Investigations of anovulation [14]:
| Investigation | Purpose | Interpretation |
|---|---|---|
| Mid-luteal progesterone [14] | Confirm ovulation | > 16 nmol/L (> 5 ng/mL) = ovulation confirmed. Low → anovulatory cycle. |
| Serial transvaginal USS (follicle tracking) | Monitor follicular development | Tracks dominant follicle growth (should reach ~18–24 mm before ovulation). In PCOS: multiple small follicles without dominant follicle development. Used during ovulation induction. |
| Endometrial assessment | Assess endometrial receptivity; exclude hyperplasia | If endometrium is thickened (> 12 mm) in an anovulatory patient, consider endometrial biopsy/sampling to exclude hyperplasia or carcinoma. |
| Tubal patency testing | Exclude tubal factor (coexisting cause of infertility) | Hysterosalpingography (HSG), HyCoSy (hystero-contrast sonography), or laparoscopy with chromotubation. Not a PCOS-specific investigation but part of complete infertility workup. |
| Partner semen analysis | Exclude male factor | Always assess both partners simultaneously. |
| Category | Investigations | Purpose |
|---|---|---|
| Exclude pregnancy | βhCG | Always first |
| Baseline hormonal panel [15][16] | FSH, LH, E2, PRL, TFT, testosterone | Assess HPO axis, exclude mimics |
| Androgen panel [15][16] | Total testosterone, SHBG, FAI, 17-OH progesterone, ± DHEA-S | Confirm biochemical HA, exclude CAH and tumour |
| Imaging | USG pelvis [15][16] (TVS preferred) | Assess PCOM, endometrial thickness, exclude other pelvic pathology |
| Exclude Cushing's | Overnight 1mg DST (if clinically suspected) | Cortisol suppression |
| Metabolic screening | OGTT, HbA1c, fasting lipids, BP, BMI, waist circumference, LFTs | Assess metabolic syndrome components |
| Fertility-specific | Mid-luteal progesterone, follicle tracking, HSG, semen analysis | When infertility is the complaint |
| Further investigations [15][16] | Karyotype (primary amenorrhoea, POI), Fragile X premutation (POI), autoimmune screening, pituitary imaging, visual field perimetry, laparoscopy/hysteroscopy | Depending on the suspected underlying cause |
| Hormonal Pattern | Diagnosis |
|---|---|
| ↑LH, normal/↓FSH, LH:FSH > 2, mildly ↑testosterone, ↓SHBG, PCOM on USS | PCOS (classic) |
| ↑↑FSH (> 25 IU/L), ↓E2, normal/↓androgens | Premature ovarian insufficiency |
| ↓LH, ↓FSH, ↓E2, normal androgens | Hypogonadotropic hypogonadism (FHA, pituitary) |
| ↑Prolactin, ↓LH/FSH | Hyperprolactinaemia |
| Abnormal TSH | Thyroid disorder |
| ↑17-OHP (> 6 nmol/L) | Non-classic CAH |
| ↑↑Testosterone (> 5 nmol/L), ± ↑DHEA-S | Androgen-secreting tumour |
| Cortisol not suppressed on DST | Cushing's syndrome |
The Classic PCOS Biochemical Profile
Remember the "LIT" mnemonic for PCOS biochemistry: LH elevated (with LH:FSH > 2), Insulin elevated (with ↓SHBG), Testosterone mildly elevated. Add to this: AMH elevated, OGTT often abnormal, and lipid profile showing ↑TG, ↓HDL-C.
High Yield Summary
Diagnostic Criteria: Current adult criteria — 2 out of 3, after excluding other causes: [1][12][17]
- Oligo-anovulation
- Clinical / biochemical hyperandrogenism
- PCOM on ultrasound (FNPO > 20 and/or ovarian volume ≥ 10 mL) OR elevated AMH in adults
Mandatory baseline investigations: FSH, LH, E2, PRL, TFT, testosterone [15][16]; plus βhCG, 17-OHP; USG pelvis [15][16]
Second-line: SHBG, 17-OH progesterone, DHEA-S [15][16]; progestogen challenge test; overnight DST if Cushing's suspected
Key hormonal pattern in PMOS/PCOS: ↑LH, normal/↓FSH, LH:FSH > 2, mildly ↑testosterone, ↓SHBG, ↑FAI, ↑AMH
PCOM criterion: USS FNPO > 20 and/or ovarian volume ≥ 10 mL; AMH can substitute for USS in adults only
Metabolic screening in ALL PMOS/PCOS patients: OGTT (preferred over fasting glucose alone), fasting lipids, BP, BMI, waist circumference, LFTs
High FSH ( > 25 IU/L) indicates ovarian insufficiency — NOT PCOS [2][4][14]
Adolescent caution: Do not use PCOM on USS or AMH for diagnosis; require both HA + persistent ovulatory dysfunction
Active Recall - PCOS Diagnostic Criteria and Investigations
References
[1] Lecture slides: GC 114. Climacteric symptoms menopause and related illness; amenorrhoea.pdf (p14) [2] Lecture slides: GC 117. I want to have a baby male and female infertility.pdf (p32, p33) [3] Senior notes: Ryan Ho Endocrine.pdf (p77) [4] Lecture slides: Block C - I want to have a baby_ male and female infertility.pdf (p11) [5] Senior notes: Maksim Medicine Notes.pdf (p79) [7] Senior notes: Ryan Ho GI.pdf (p309) [8] Senior notes: Maksim Medicine Notes.pdf (p103 — Hyperandrogenism) [9] Senior notes: Ryan Ho Endocrine.pdf (p74 — CAH) [10] Senior notes: Maksim Medicine Notes.pdf (p99 — Cushing's syndrome) [11] Senior notes: Ryan Ho Chemical Path.pdf (p29 — Diagnosis of Cushing Syndrome) [12] Lecture slides: Block C - Climacteric symptoms_ menopause and related illness; amenorrhoea.pdf (p9) [14] Lecture slides: GC 117. I want to have a baby male and female infertility.pdf (p24, p33) [15] Lecture slides: GC 114. Climacteric symptoms menopause and related illness; amenorrhoea.pdf (p19, p20) [16] Lecture slides: Block C - Climacteric symptoms_ menopause and related illness; amenorrhoea.pdf (p11) [17] Teede HJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Fertility and Sterility. 2023. [18] Teede HJ, et al. Polyendocrine metabolic ovarian syndrome, the new name for polycystic ovary syndrome: a multistep global consensus process. Lancet. 2026.
Management of PMOS (formerly PCOS)
Before diving into specifics, understand that PMOS/PCOS management is symptom-driven and individualised. There is no single "cure" — PMOS/PCOS is a chronic condition. Management is tailored to what the patient's primary concern is at that point in her life:
- Is she bothered by irregular periods and worried about endometrial cancer?
- Is she distressed by hirsutism and acne?
- Is she trying to conceive?
- Does she need metabolic risk reduction?
These goals often overlap but may also conflict (e.g., COC pills treat hirsutism and regulate periods, but they are contraceptive — useless if the patient wants a baby). So the first question on the ward round is always: "What is your main concern right now?"
Amenorrhoea is a symptom, NOT a diagnosis. Need to look for the underlying cause and treat accordingly. [12]
The lecture slides give us a clear framework for PMOS/PCOS management [1][12]:
Polycystic Ovary Syndrome management:
Treatment Modalities: Detailed Discussion
Weight reduction [1][12] is the cornerstone of PCOS management, applicable to every patient regardless of her primary concern. Even 5–10% weight loss can:
- Restore ovulatory cycles in up to 50–60% of overweight/obese PCOS women.
- Reduce circulating androgens by 20–30%.
- Improve insulin sensitivity → ↓insulin levels → ↓ovarian androgen production + ↑SHBG → ↓free testosterone.
- Improve lipid profile, reduce BP, and decrease long-term CVD and T2DM risk.
- Improve IVF outcomes if fertility treatment is needed.
Why does weight loss work so powerfully? Because obesity amplifies the central pathophysiological driver — insulin resistance. Reducing adiposity breaks the vicious cycle: ↓Adipose tissue → ↓FFA + ↓adipokines → ↓insulin resistance → ↓compensatory hyperinsulinaemia → ↓ovarian androgen production + ↑hepatic SHBG → ↓free testosterone → restored follicular development → ovulation.
| Component | Detail | Mechanism |
|---|---|---|
| Dietary modification | Caloric restriction (500–750 kcal deficit/day); low glycaemic index (GI) diet preferred; Mediterranean-style diet or DASH diet [17] | Low-GI foods → slower glucose absorption → lower insulin spikes → ↓hyperinsulinaemia. Minimize high energy food, esp those with high glycemic index (GI) and glycemic load (GL) [17]. |
| Exercise | ≥ 150 min/week moderate-intensity aerobic activity (brisk walking, cycling, swimming) + resistance training ≥ 2 times/week [17] | Exercise → ↑AMPK activation → ↑glucose uptake by skeletal muscle + ↑FFA oxidation → ↓insulin resistance, independent of weight loss. Resistance training increases lean muscle mass → ↑basal metabolic rate. |
| Behavioural support | Goal-setting, self-monitoring, cognitive-behavioural therapy | Sustaining lifestyle change is the hardest part. PCOS patients often have comorbid depression/anxiety that undermines motivation. Dietitian and psychologist input are valuable. |
| Psychological support | Screen for depression, anxiety, disordered eating; refer as needed | Prevalence of depression 28–64% in PCOS. Body image distress from hirsutism/acne/obesity. Untreated psychological morbidity worsens adherence to lifestyle change. |
Lifestyle First, Always
Every international guideline recommends lifestyle modification as first-line therapy for ALL aspects of PMOS/PCOS — menstrual irregularity, hyperandrogenism, infertility, and metabolic risk. Pharmacotherapy is always adjunctive to lifestyle, not a substitute. This is a common exam point.
Menstrual regulation: prevent endometrial hyperplasia/CA [1][12]
Why is this critical? Chronic anovulation → continuous unopposed oestrogen (from peripheral aromatisation of excess androgens to oestrone in adipose tissue) → endometrial proliferation without progesterone-induced secretory transformation and shedding → endometrial hyperplasia → potential progression to endometrial carcinoma (Type I, oestrogen-dependent). The risk is 2–6× higher in PCOS.
Therefore, all anovulatory PCOS patients who are not trying to conceive must have regular endometrial shedding — either by inducing withdrawal bleeds or by directly protecting the endometrium with progestogen.
| Modality | Regimen | Mechanism | Indications | Contraindications / Cautions |
|---|---|---|---|---|
| Periodic progestogen for withdrawal bleeding [1][12] | Medroxyprogesterone acetate (MPA) 10 mg/day for 10–14 days every 1–3 months, or micronised progesterone 200–400 mg/day for 10–14 days | Exogenous progestogen converts proliferative endometrium to secretory phase → organised shedding (withdrawal bleed) upon cessation → "resets" the endometrium. | Women who do NOT need contraception and have no significant hyperandrogenic symptoms. Simple, minimal systemic effects. | Pregnancy (always do βhCG first). Irregular compliance may result in prolonged gaps without endometrial protection. |
| COC pills [1][12] | Ethinyloestradiol (EE) 20–35 µg + progestogen (e.g., levonorgestrel, norgestimate, desogestrel, or cyproterone acetate — see anti-androgens) | Multiple mechanisms: (1) Progestogen component opposes endometrial proliferation → prevents hyperplasia. (2) Oestrogen component ↑hepatic SHBG → ↓free testosterone. (3) Oestrogen + progestogen suppress GnRH/LH → ↓ovarian androgen production. (4) Provide regular withdrawal bleeds. | First-line for women wanting both menstrual regulation AND treatment of hirsutism/acne [1][12]. Also provides reliable contraception. | Absolute C/I: migraine with aura, active/history of VTE/PE, ischaemic heart disease, stroke, breast cancer, liver disease, uncontrolled HTN, smoking ≥ 15 cig/day if age ≥ 35, < 6 weeks postpartum if breastfeeding. Cautions: obesity (↑VTE risk), family history of VTE, immobilisation. |
| Levonorgestrel intrauterine system (LNG-IUS / Mirena) | Releases 20 µg levonorgestrel/day locally into the uterine cavity | Local progestogen directly suppresses endometrial proliferation → endometrial atrophy → protects against hyperplasia. Minimal systemic progestogen effects. | Women who cannot take COCs (e.g., VTE risk, smokers > 35); women wanting long-acting reversible contraception (LARC); excellent endometrial protection. | Uterine anomalies (relative), active PID, unexplained vaginal bleeding (investigate first), pregnancy. |
How Often to Induce Withdrawal Bleeds?
International guidance recommends ensuring endometrial shedding at least every 3 months (i.e., minimum 4 withdrawal bleeds per year). If the endometrium becomes ≥ 12 mm on USS in an anovulatory patient, consider endometrial biopsy to exclude hyperplasia before starting treatment.
3. Management of Hyperandrogenic Symptoms
Hirsutism: COC pills, cosmetic measures, anti-oestrogens [1][12]
Hirsutism treatment requires patience — existing terminal hairs will not revert to vellus hairs with medical therapy alone (because the hair follicle has already been "programmed" by androgens). Medical therapy prevents new terminal hair growth and slows the growth rate of existing ones. Cosmetic measures address existing hair. Allow 6–12 months for any medical treatment to show full effect (hair growth cycles are long).
| Treatment | Mechanism | Detail | Onset of Effect |
|---|---|---|---|
| COC pills — first line [1][12] | (1) ↑SHBG → ↓free testosterone. (2) Suppress LH → ↓ovarian androgen production. (3) Mild direct anti-androgen effect of some progestogens (e.g., cyproterone acetate, drospirenone). | Prefer COC containing anti-androgenic progestogen (e.g., cyproterone acetate (Diane-35), drospirenone (Yasmin)). All COCs have some benefit via ↑SHBG, but anti-androgenic progestogens provide additional benefit. | 6–12 months |
| Spironolactone | "Spiro" = spiral (steroid structure). An aldosterone antagonist that also has potent anti-androgen activity: (1) Blocks the androgen receptor (AR). (2) Inhibits 5α-reductase → ↓conversion of testosterone to the more potent DHT. (3) Mildly ↓testosterone synthesis. | Dose: 50–200 mg/day. Often combined with COC for synergy and to prevent menstrual irregularity (spironolactone alone can cause breakthrough bleeding) and to provide contraception (spironolactone is teratogenic — feminises male fetuses). | 6–12 months |
| Cyproterone acetate (CPA) | Potent progestogen with strong anti-androgen activity. (1) AR antagonist. (2) Inhibits gonadotropin secretion → ↓ovarian androgens. (3) Inhibits 5α-reductase. | Can be used as the progestogen component of COC (Diane-35: EE 35 µg + CPA 2 mg), or as higher-dose add-on (10–50 mg/day on days 1–10 of COC cycle = "reverse sequential regimen"). S/E: hepatotoxicity (rare but serious at high doses), weight gain, depression, ↓libido, VTE risk. | 6–12 months |
| Finasteride | "Fin" = five (targets 5α-reductase type 2). Blocks conversion of testosterone to DHT in skin. DHT is the main androgen driving hair follicle transformation. | 5 mg/day. Less commonly used than spironolactone. Also teratogenic — must use with effective contraception. | 6–12 months |
| Flutamide | Non-steroidal pure AR antagonist. Blocks androgen binding at the receptor. | Effective but rarely used due to risk of fatal hepatotoxicity. Not recommended as first-line. | 6–12 months |
| Cosmetic measures [1][12] | Physical removal or camouflage of existing terminal hairs. | Laser hair removal (targets melanin in hair follicle → photothermal destruction — works best on dark hair, light skin), electrolysis (destroys individual follicles with electric current — effective for all hair types), intense pulsed light (IPL), shaving, waxing, threading, depilatory creams. Topical eflornithine cream (Vaniqa): inhibits ornithine decarboxylase in hair follicle → slows hair growth rate. Applied to face twice daily — works while used, hair regrows on cessation. | Immediate (physical methods); 4–8 weeks (eflornithine) |
Anti-androgen + Contraception = Mandatory Pairing
Spironolactone, cyproterone acetate, and finasteride are all teratogenic. If used in a woman of reproductive age, they must be combined with effective contraception (typically a COC). This is a non-negotiable clinical rule and a common exam point. The reason: these drugs cross the placenta and can feminise a male fetus (ambiguous genitalia, hypospadias).
Acne in PCOS is driven by hyperandrogenism → ↑sebum production [6]. The approach follows standard acne management guidelines but with emphasis on hormonal therapy [6][18]:
| Severity | Treatment | Notes |
|---|---|---|
| Mild | Topical retinoid (comedonal) or benzoyl peroxide (inflammatory), or combination [18] | Standard first-line for any acne. |
| Moderate | Topical combination Tx + Oral Abx + topical retinoid + BP [18]. Add COCP or oral spironolactone (F) [18] | Combined OC pills: downregulate HPG axis → ↓ovarian androgen secretion [18]. Adding COC addresses the hormonal root cause. |
| Severe | Oral Abx + topical combination Tx; Oral isotretinoin [18]. Add COCP or oral spironolactone (F) [18] | Oral isotretinoin (Roaccutane): shrinkage of sebaceous glands with ↓↓secretion + ↑keratinocyte differentiation → ↓↓↓comedogenesis [18]. Must use contraception — isotretinoin is highly teratogenic. |
- First-line: COC pills (↑SHBG, ↓free testosterone) + topical minoxidil 2–5% (stimulates hair follicle growth via vasodilation and direct follicular stimulation — not anti-androgenic, works independently).
- Second-line: Add spironolactone or finasteride (with contraception).
- Refer to dermatology for refractory cases.
Fertility: ovulation induction by letrozole / gonadotrophin [1][12]
This is relevant when the patient's primary concern is conception. The fundamental problem is anovulation — so the goal is to induce ovulation while minimising the risk of ovarian hyperstimulation syndrome (OHSS) and multiple pregnancy, to which PCOS patients are especially susceptible due to their multiple follicles.
Pre-conception optimisation:
- Weight reduction [1][12] — even 5–10% weight loss can restore spontaneous ovulation.
- Folic acid supplementation (0.4–5 mg/day).
- Optimise glycaemic control if IGT/T2DM.
- Screen and treat partner (semen analysis) and tubal factors.
- Stop all teratogenic drugs (spironolactone, finasteride, isotretinoin, statins, ACEi/ARB).
| Line | Treatment | Mechanism | Key Points |
|---|---|---|---|
| First line: Letrozole [1][12] | "Letro" = let; "zole" = aromatase inhibitor (azole class). Letrozole is a third-generation aromatase inhibitor. It blocks aromatase (CYP19A1) → ↓peripheral conversion of androgens to oestrogens → ↓negative feedback on hypothalamus/pituitary → ↑FSH release → follicular development → ovulation. | Dose: 2.5–7.5 mg/day for 5 days, starting day 2–5 of cycle (after spontaneous or progestogen-induced bleed). Superior to clomifene citrate (the traditional first-line) — the NEJM 2014 trial showed higher ovulation and live birth rates with letrozole vs clomifene in PCOS. Endorsed as first-line in international guideline updates. Advantages: Shorter half-life than clomifene → less anti-oestrogenic effect on endometrium (clomifene thins the endometrium, which is counterproductive for implantation). Lower multiple pregnancy rate. Monitoring: Serial USS for follicle tracking. | |
| Clomifene citrate (CC) | Selective oestrogen receptor modulator (SERM). Blocks oestrogen receptors at the hypothalamus → hypothalamus "thinks" oestrogen is low → ↑GnRH → ↑FSH → follicular development. | Dose: 50–150 mg/day for 5 days, starting day 2–5 of cycle. Was the traditional first-line for decades. Disadvantages vs letrozole: Anti-oestrogenic effect on endometrium (thins it → ↓implantation), anti-oestrogenic effect on cervical mucus (thickens it → ↓sperm penetration), higher rate of multiple pregnancy (~10% twins). Maximum 6 ovulatory cycles — if no pregnancy, move to next line. Now considered second-line after letrozole in international guidance. | |
| Second line: Gonadotrophins [1][12] | Exogenous FSH (e.g., recombinant FSH — follitropin alfa/beta; or human menopausal gonadotrophin, HMG — contains both FSH and LH activity) [19] directly stimulates follicular development, bypassing the hypothalamic-pituitary level. | Low-dose step-up protocol (critical in PCOS): Start with a low dose of FSH (37.5–50 IU/day SC) → increase by 37.5 IU increments every 7–14 days until a single dominant follicle develops (18–22 mm on USS). Why low-dose step-up? PCOS ovaries have many FSH-sensitive antral follicles → standard-dose gonadotrophins carry very high risk of multi-follicular development → OHSS and multiple pregnancy. The step-up protocol aims to find the patient's individual "FSH threshold" — the minimum FSH dose that recruits just one dominant follicle. Trigger ovulation with hCG injection (e.g., Ovitrelle 250 µg SC) when lead follicle reaches 18 mm. Requires intensive monitoring: Serial TVS + serum oestradiol. Cancel cycle if > 3 follicles ≥ 14 mm or E2 > 10,000 pmol/L → ↑OHSS risk. | |
| Third line: Laparoscopic ovarian drilling (LOD) | Laparoscopic electrocautery or laser to the ovarian surface (typically 4–10 punctures per ovary, 5 mm depth, 40W for 4 seconds each). | Mechanism: Destroys androgen-producing ovarian stromal tissue → ↓local androgen concentration → ↓intra-follicular androgen excess → restored FSH sensitivity → spontaneous ovulation. Also ↓AMH and inhibin B → ↑FSH. Advantages: No risk of OHSS or multiple pregnancy; can restore spontaneous ovulation for months-years. Disadvantages: Requires general anaesthesia; surgical risks; risk of periovarian adhesions (→ can worsen fertility); limited duration of effect (median 12 months). Indication: Clomifene/letrozole-resistant PMOS/PCOS, or when gonadotrophins are not available/feasible, or patient preference (avoids injections and monitoring). | |
| Fourth line: In vitro fertilisation (IVF) | Controlled ovarian hyperstimulation with gonadotrophins → oocyte retrieval → in vitro fertilisation → embryo transfer. | Reserved for women who fail ovulation induction, or who have coexisting tubal factor or male factor infertility. PCOS patients are at high risk of OHSS during IVF → use GnRH antagonist protocol with agonist trigger (instead of hCG trigger) to reduce OHSS risk. Consider elective single embryo transfer to avoid multiple pregnancy. |
Letrozole vs Clomifene: Know This for Exams
International guidelines recommend letrozole as first-line for ovulation induction in PMOS/PCOS, replacing clomifene citrate which was the historical gold standard. Key reasons: (1) Higher ovulation and live birth rates (NEJM 2014 trial), (2) Shorter half-life → less anti-oestrogenic endometrial effect, (3) Lower multiple pregnancy rate. The HKUMed lecture slides explicitly list letrozole [1][12] as the first-line agent.
Metformin for Fertility?
Metformin was previously widely used for ovulation induction in PCOS. Current evidence shows it is inferior to letrozole and clomifene as monotherapy for ovulation induction. It may have a role as an adjunct to clomifene in clomifene-resistant patients, or in reducing OHSS risk during IVF. It is NOT listed as a primary fertility treatment in the lecture slides.
Metabolic disorder in long term [1][12]
PCOS is a lifelong metabolic condition. Even if reproductive symptoms improve with age (as ovarian function declines), metabolic risk persists and often worsens.
| Target | Intervention | Detail |
|---|---|---|
| Insulin resistance / IGT / T2DM | Lifestyle modification (first-line for all). Metformin if IGT or T2DM develops, or as adjunct for insulin resistance. | Metformin — "met" = methyl, "formin" = biguanide class. MoA: (1) ↓hepatic glucose production (↓gluconeogenesis), (2) ↑insulin sensitivity in peripheral tissues (↑AMPK activation → ↑glucose uptake), (3) ↓intestinal glucose absorption. In PCOS: ↓insulin levels → ↓ovarian androgen production → may improve menstrual regularity (modest effect). Dose: Start 500 mg OD with meals → titrate to 1500–2000 mg/day. S/E: GI upset (nausea, diarrhoea, bloating — ↓with slow titration and extended-release formulation), lactic acidosis (rare, mainly if renal impairment). C/I: eGFR < 30, severe hepatic impairment, acute illness with tissue hypoperfusion, heavy alcohol use. |
| Dyslipidaemia | Lifestyle modification first. Statins if indicated by CVD risk assessment. | Typical pattern: ↑LDL-C, TG, ↓HDL-C [3]. Statin therapy follows standard cardiovascular risk assessment guidelines (not PCOS-specific). |
| Hypertension | Lifestyle (↓salt, ↑exercise, weight loss). Antihypertensives if persistent. | ACEi or ARB preferred in young women (but absolutely C/I in pregnancy — switch to labetalol/methyldopa/nifedipine if planning conception). |
| NAFLD | Weight loss, avoid hepatotoxins. | Considered the hepatic manifestation of metabolic syndrome [7]. No specific pharmacotherapy for NAFLD in PCOS beyond weight loss. Monitor LFTs. |
| Bariatric surgery | For severe obesity refractory to medical treatment. | Indications for bariatric surgery in Asians: failed medical treatment + BMI ≥ 35, or BMI ≥ 30 with T2DM [20]. Bariatric surgery in severely obese PCOS patients can dramatically improve insulin resistance, restore ovulation, and reduce androgen levels. |
| Psychological wellbeing | Screen for depression, anxiety, eating disorders. Refer for CBT or pharmacotherapy as needed. | Prevalence of depression 28–64%, anxiety 34–57% in PCOS. These comorbidities independently worsen metabolic outcomes and adherence. |
| OSA screening | Epworth Sleepiness Scale. Polysomnography if symptomatic or high BMI. | ↑Prevalence in PCOS due to obesity + androgen effects on upper airway. Untreated OSA worsens insulin resistance and CVD risk. |
Metformin occupies a somewhat controversial position in PCOS management. Let's clarify:
| Indication | Evidence | Current Recommendation |
|---|---|---|
| Ovulation induction (primary) | Inferior to letrozole and clomifene as monotherapy | NOT first-line. May be used as adjunct to clomifene in CC-resistant patients. |
| Menstrual regulation | Modest improvement in cycle regularity (inferior to COC) | Can be considered if COC is contraindicated. |
| Insulin resistance / metabolic risk | Improves insulin sensitivity, may ↓progression to T2DM | Reasonable in women with IGT/IFG, especially if overweight. |
| Weight loss | Modest effect (~1–2 kg over 6 months; far less than lifestyle or bariatric surgery) | Adjunct to lifestyle modification, not a weight-loss drug per se. |
| Hirsutism/acne | Minimal direct effect on hyperandrogenic symptoms | NOT recommended for hirsutism/acne. |
| Prevention of OHSS during IVF | Some evidence of ↓OHSS risk when used during IVF stimulation | May be used as adjunct during IVF in high-risk patients. |
| Symptom / Goal | First-Line | Second-Line | Third-Line | Key Principle |
|---|---|---|---|---|
| ALL patients | Lifestyle: weight reduction, diet, exercise [1][12] | — | — | Foundation of all management |
| Menstrual regulation [1][12] | COC pills or periodic progestogen [1][12] | LNG-IUS (Mirena) | — | Prevent endometrial hyperplasia/CA [1][12] |
| Hirsutism [1][12] | COC pills (with anti-androgenic progestogen) + cosmetic measures [1][12] | Add spironolactone or CPA | Finasteride, flutamide (rarely) | Must use contraception with anti-androgens |
| Acne | Topical retinoids/BP + COC pills | Add oral Abx ± spironolactone | Oral isotretinoin (with contraception) | Address hormonal root cause with COC |
| Alopecia | COC pills + topical minoxidil | Spironolactone/finasteride | Dermatology referral | Slow response — months to see improvement |
| Infertility [1][12] | Letrozole [1][12] | Gonadotrophins (low-dose step-up) [1][12] | Laparoscopic ovarian drilling → IVF | Pre-optimise weight; letrozole is now first-line |
| Metabolic risk [1][12] | Lifestyle + metabolic screening | Metformin (for IGT/T2DM); statins/antihypertensives as indicated | Bariatric surgery if BMI ≥ 35 + comorbidity [20] | Lifelong monitoring required |
| Assessment | Frequency | Rationale |
|---|---|---|
| OGTT or HbA1c | At diagnosis, then every 1–3 years (annually if high risk: BMI > 25, FHx T2DM, advancing age) | 30–40% of PCOS women develop IGT by age 30; up to 10% develop T2DM |
| Fasting lipid profile | At diagnosis, then every 1–2 years | Atherogenic dyslipidaemia |
| BP, BMI, waist circumference | Every visit | Metabolic syndrome components |
| Endometrial assessment | If amenorrhoea > 3 months without endometrial protection; if abnormal bleeding | Risk of endometrial hyperplasia/carcinoma |
| Psychological screening | At diagnosis, then periodically | High prevalence of depression/anxiety |
| Reassess treatment goals | Annually, or at life-stage transitions (e.g., desire for pregnancy) | Treatment strategy changes based on whether fertility is desired |
High Yield Summary
Management is symptom-driven and individualised. Lifestyle modification (weight reduction, diet, exercise) is the foundation for ALL patients. [1][12]
PMOS/PCOS Management Framework (from lecture slides): [1][12]
- Weight reduction — 5–10% loss can restore ovulation and improve metabolic profile
- Menstrual regulation: prevent endometrial hyperplasia/CA — periodic progestogen for withdrawal bleeding or COC pills
- Hirsutism: COC pills, cosmetic measures, anti-oestrogens — anti-androgens (spironolactone, CPA) must be combined with contraception (teratogenic)
- Fertility: ovulation induction by letrozole / gonadotrophin — letrozole is first-line (superior to clomifene); gonadotrophins use low-dose step-up protocol to minimise OHSS
- Metabolic disorder in long term — screen and treat IGT/T2DM, dyslipidaemia, HTN, NAFLD; metformin for insulin resistance; bariatric surgery if BMI ≥ 35 + comorbidity
Key rules:
- Anti-androgens (spironolactone, CPA, finasteride) are teratogenic → always combine with effective contraception
- Letrozole has replaced clomifene as first-line for ovulation induction (international guideline updates)
- Endometrial protection (minimum 4 withdrawal bleeds/year) is mandatory in anovulatory women
- Unopposed oestrogen is dangerous in women without hysterectomy as it can ↑risk of CA endometrium [19]
Active Recall - PMOS/PCOS Management
References
[1] Lecture slides: GC 114. Climacteric symptoms menopause and related illness; amenorrhoea.pdf (p28) [3] Senior notes: Ryan Ho Endocrine.pdf (p77) [6] Senior notes: Ryan Ho Rheumatology.pdf (p126 — Acne Vulgaris) [7] Senior notes: Ryan Ho GI.pdf (p309 — NAFLD) [12] Lecture slides: Block C - Climacteric symptoms_ menopause and related illness; amenorrhoea.pdf (p14) [17] Senior notes: Ryan Ho Endocrine.pdf (p83 — Lifestyle measures) [18] Senior notes: Ryan Ho Rheumatology.pdf (p127–128 — Acne management) [19] Senior notes: Ryan Ho Endocrine.pdf (p113 — Gonadotropin deficiency management) [20] Senior notes: Maksim Surgery Notes.pdf (p75 — Bariatric surgery)
Complications of PMOS (formerly PCOS)
PMOS/PCOS is far more than a reproductive disorder. It is a systemic endocrine-metabolic condition with complications spanning reproductive, metabolic, oncological, and psychological domains. The complications are best understood by tracing them back to the core pathophysiological drivers: hyperandrogenism, chronic anovulation, insulin resistance/hyperinsulinaemia, and obesity.
Think of PMOS/PCOS complications in five domains:
- Reproductive complications (from anovulation and hyperandrogenism)
- Metabolic complications (from insulin resistance)
- Cardiovascular complications (from metabolic syndrome clustering)
- Oncological complications (from unopposed oestrogen)
- Psychological complications (from disease burden and hormonal imbalance)
1. Reproductive Complications
↓Fertility (due to PCOS) [3]
- Mechanism: Chronic anovulation → no oocyte release → inability to conceive. PCOS accounts for ~80% of all anovulatory infertility cases.
- Even when ovulation is achieved (spontaneously or with treatment), oocyte quality may be suboptimal due to prolonged follicular arrest in a hyperandrogenic, hyperinsulinaemic milieu. Endometrial receptivity may also be impaired (chronic unopposed oestrogen → desynchronised endometrial development).
- Key point: Infertility in PCOS is usually treatable — most women can achieve pregnancy with lifestyle modification ± ovulation induction. The prognosis for fertility is generally good compared to other causes of infertility (e.g., POI, severe tubal factor).
When PCOS women do become pregnant, they face significantly elevated risks:
| Complication | Risk Increase | Pathophysiological Basis |
|---|---|---|
| Gestational diabetes mellitus (GDM) | 3× higher [21][22] | Pre-existing insulin resistance is amplified by the normal diabetogenic hormonal milieu of pregnancy (human placental lactogen, cortisol, progesterone all worsen insulin resistance). The β-cells, already stressed by chronic hyperinsulinaemia, cannot compensate → hyperglycaemia. Effects on pregnancy — Maternal: increased risk of pre-eclampsia, urinary tract infection, preterm labour; increased incidence of caesarean section and instrumental delivery [21]. |
| Pre-eclampsia | 3–4× higher [21] | Insulin resistance → endothelial dysfunction → impaired trophoblast invasion and spiral artery remodelling → placental ischaemia → release of anti-angiogenic factors (sFlt-1, soluble endoglin) → systemic endothelial dysfunction → hypertension + proteinuria. Chronic inflammation and obesity further amplify the risk. |
| Preterm birth | 2× higher | Multifactorial: associated with pre-eclampsia, GDM, polyhydramnios, and cervical insufficiency. Also possibly related to chronic low-grade inflammation. |
| Large-for-gestational-age (LGA) / Macrosomia | Increased [22] | If GDM develops → maternal hyperglycaemia → glucose crosses placenta → fetal hyperinsulinaemia → fetal anabolism → excessive fetal growth (Pedersen hypothesis). Fetal/Neonatal: large-for-gestational age, asphyxia and birth trauma [22]. |
| Caesarean section | Increased [21] | Due to macrosomia, failed induction, and maternal comorbidities. |
| Miscarriage | Possibly 2× higher (debated) | Mechanisms unclear — possibly related to hyperandrogenism (direct embryotoxicity), hyperinsulinaemia (impaired endometrial decidualisation), elevated PAI-1 (impaired fibrinolysis → placental thrombosis), or obesity. The evidence is mixed and the independent contribution of PCOS vs. obesity is difficult to disentangle. |
| Congenital malformations (if GDM/pre-existing DM) | Increased if hyperglycaemia in organogenesis [22] | Increased risk of congenital malformations: neural tube, skeletal, cardiac, renal, gastrointestinal [22]. Hyperglycaemia during the first trimester → oxidative stress → disruption of embryonic organogenesis. This risk is mainly relevant for women with pre-existing DM or poorly controlled early GDM. |
| Fetal programming | Long-term [22] | Long-term consequences on the offspring: fetal programming effect on metabolic and cardiovascular diseases [22]. Intrauterine exposure to hyperglycaemia and hyperinsulinaemia → epigenetic changes in fetal metabolic programming → ↑risk of obesity, T2DM, CVD, and even PCOS in offspring. This creates an intergenerational cycle. |
| Ovarian hyperstimulation syndrome (OHSS) | Increased during fertility treatment | PCOS ovaries contain multiple FSH-sensitive antral follicles → excessive response to gonadotrophins → multi-follicular development → massive ovarian enlargement, capillary leak syndrome → ascites, pleural effusion, haemoconcentration, VTE, renal failure (severe OHSS). This is an iatrogenic complication of fertility treatment, not PCOS itself, but PCOS is the single biggest risk factor for OHSS. |
PCOS Pregnancy = High-Risk Pregnancy
Every PCOS pregnancy should be managed as a high-risk pregnancy. This means: early OGTT screening for GDM (at booking AND at 24–28 weeks), vigilant monitoring for pre-eclampsia, serial growth scans for macrosomia, and strict glycaemic control — insulin usually needed [23]. Pre-conception optimisation (weight loss, folic acid, stopping teratogenic drugs) is essential.
- Some studies suggest PCOS women have higher rates of early miscarriage (first trimester), though this is debated.
- Proposed mechanisms: hyperandrogenism → impaired endometrial receptivity; hyperinsulinaemia → ↑PAI-1 (plasminogen activator inhibitor-1) → hypofibrinolysis → placental micro-thrombosis; obesity → chronic inflammation.
- Metformin was previously proposed to reduce miscarriage risk in PCOS, but evidence is inconsistent and it is not recommended solely for miscarriage prevention.
2. Metabolic Complications
These are the complications that drive long-term morbidity and mortality in PCOS. They are all consequences of the central pathophysiological driver: insulin resistance.
Metabolic syndrome: cluster of metabolic disorders due to insulin resistance → Manifestations: Type 2 DM, Polycystic ovarian syndrome (PCOS) [3]
- Prevalence: 30–40% of PCOS women develop impaired glucose tolerance (IGT) by age 30; 5–10% have frank T2DM. The risk of conversion from IGT to T2DM is ~5–10% per year in PCOS (higher than the general population's 1–2%/year).
- Why so high? PCOS involves intrinsic insulin resistance (not just obesity-mediated) + compensatory hyperinsulinaemia → progressive β-cell exhaustion over years. Progression: hyperinsulinaemic euglycaemia → impaired glucose tolerance → early T2DM → late T2DM with absolute insulin deficiency [3].
- Key screening: OGTT (preferred over fasting glucose alone — captures post-challenge hyperglycaemia which is often the first abnormality in PCOS).
- Once T2DM develops, all standard diabetic complications apply — macrovascular (IHD, stroke, PVD) and microvascular (retinopathy, nephropathy, neuropathy) [24].
Dyslipidaemia, i.e. ↑LDL-C, TG, ↓HDL-C [3]
- Typical pattern: ↑Triglycerides, ↓HDL-C, ↑small dense LDL (the most atherogenic LDL subtype). Total LDL-C may be only mildly elevated, but the qualitative shift to small dense LDL is highly pro-atherogenic.
- Mechanism: Insulin resistance → ↑hepatic VLDL production (driven by ↑FFA flux from adipose tissue to liver) → ↑TG; CETP-mediated exchange of TG for cholesterol esters between VLDL and HDL → TG-enriched HDL → faster hepatic clearance → ↓HDL-C; LDL particles become TG-enriched → hepatic lipase cleaves TG → smaller, denser LDL.
- Management: Lifestyle first; statins if indicated by cardiovascular risk assessment.
Diagnostic criteria of metabolic syndrome: Presence of ≥ 3 of: (1) Glucose intolerance or type 2 DM; (2) Hypertension; (3) Hypertriglyceridaemia; (4) ↓HDL-C; (5) Central obesity [3]
- PCOS dramatically increases the risk of meeting metabolic syndrome criteria. Studies show 30–40% of PCOS women have metabolic syndrome (vs ~10% of age-matched controls).
- The clustering of these risk factors creates a multiplicative (not just additive) cardiovascular risk.
Non-alcoholic fatty liver disease (NAFLD) — considered the hepatic manifestation of metabolic syndrome [7]
- Prevalence in PCOS: 30–40% (2–3× higher than age-matched controls).
- Mechanism: Insulin resistance → ↑hepatic FFA flux → overwhelmed hepatic export/catabolism → fat accumulation (steatosis) → oxidative stress, lipotoxicity → steatohepatitis (NASH) → fibrosis → cirrhosis.
- Hyperandrogenism may independently contribute to hepatic steatosis (androgens promote hepatic lipogenesis).
- Screening: LFTs at diagnosis; liver USS if ALT elevated. Non-invasive fibrosis scores (FIB-4, NFS) for risk stratification.
Respiratory: obesity-hypoventilation syndrome, dyspnoea, OSA [3]
- Prevalence in PCOS: 5–30× higher than age-matched women.
- Mechanism: (1) Obesity → ↑pharyngeal fat deposition → upper airway narrowing → collapsibility during sleep; (2) Androgens may directly affect upper airway muscle tone and central respiratory drive; (3) Insulin resistance is independently associated with OSA severity.
- Consequences: Untreated OSA worsens insulin resistance (via sympathetic activation and intermittent hypoxia), exacerbates hypertension, and increases cardiovascular risk — creating another vicious cycle.
- Screening: Epworth Sleepiness Scale; polysomnography if symptomatic.
CVS: HTN, CAD, stroke [3]
- PCOS women have a clustering of cardiovascular risk factors from young age: insulin resistance, dyslipidaemia, hypertension, chronic inflammation, endothelial dysfunction, and obesity.
- Subclinical atherosclerosis markers (carotid intima-media thickness, coronary artery calcification) are increased in PCOS women compared to age-matched controls, even in lean PCOS patients.
- Hypertension: Present in 10–30% of PCOS women. Mechanism: insulin resistance → ↑renal sodium reabsorption, sympathetic activation, endothelial dysfunction, ↑angiotensinogen production from adipose tissue.
- Whether PCOS is an independent CVD risk factor (beyond the conventional risk factors it causes) is still debated. Large prospective studies have shown inconsistent results regarding hard CVD outcomes (MI, stroke), partly because PCOS women are young and events take decades to manifest. The current consensus is that PCOS amplifies conventional risk factors and that aggressive risk factor management is warranted.
Young Women, Old Problems
The tragedy of PCOS is that it exposes young women (20s–30s) to metabolic risk factors that are typically seen in middle-aged men. A 25-year-old with PCOS may already have insulin resistance, dyslipidaemia, fatty liver, and subclinical atherosclerosis. Without intervention, she faces a lifetime of accelerated cardiovascular ageing. This is why metabolic disorder in long term [1][12] management is a core pillar — it's not just about periods and hirsutism.
4. Oncological Complications
Menstrual regulation: prevent endometrial hyperplasia/CA [1][12]
This is the most important oncological complication. The lecture slides explicitly highlight it as a management priority [1][12].
- Risk: 2–6× increased risk of endometrial carcinoma compared to age-matched women.
- Mechanism (from first principles):
- Chronic anovulation → no corpus luteum → no progesterone production.
- Excess androgens are peripherally aromatised to oestrone (a weak oestrogen) in adipose tissue (more so in obese women, who have more aromatase-expressing adipose tissue).
- Oestrone stimulates endometrial proliferation without progesterone opposition (unopposed oestrogen).
- The endometrium continuously proliferates → disorganised growth → simple hyperplasia → complex hyperplasia → atypical hyperplasia → Type I (oestrogen-dependent) endometrial carcinoma.
- This process takes years but can occur in women as young as their 20s–30s in PCOS.
- Prevention: This is why periodic progestogen for withdrawal bleeding and COC pills [1][12] are so important — they oppose oestrogen-driven endometrial proliferation. Minimum 4 withdrawal bleeds per year. LNG-IUS (Mirena) provides excellent endometrial protection.
- Screening: If amenorrhoea > 3 months without endometrial protection, check endometrial thickness on USS. If ≥ 12 mm or irregular bleeding pattern → endometrial biopsy (Pipelle sampling) to exclude hyperplasia/carcinoma.
| Cancer | Risk | Evidence / Mechanism |
|---|---|---|
| Breast cancer [3] | Mildly elevated (debated) | Chronic oestrogen exposure may promote oestrogen receptor-positive breast cancer. However, most studies show the risk increase is modest and may be largely confounded by obesity (an independent breast cancer risk factor). Current guidance does not recommend enhanced breast cancer screening beyond standard age-appropriate guidelines. |
| Ovarian cancer | Uncertain / not significantly increased | Despite the old name "polycystic ovary syndrome," PMOS/PCOS does not significantly increase abnormal ovarian cysts and does not clearly increase ovarian cancer risk. Some early studies suggested a mild association, but larger meta-analyses have not confirmed an independent risk after adjusting for parity, OCP use, and BMI. |
| Colorectal cancer (indirect) | Possibly increased via metabolic risk | Insulin resistance, hyperinsulinaemia, and obesity are established risk factors for colorectal cancer. This is a metabolic-mediated risk rather than a direct PCOS effect. |
Psychological: poor self-esteem, depression [3]
This is frequently underestimated but has profound impact on quality of life.
| Complication | Prevalence in PCOS | Mechanism |
|---|---|---|
| Depression | 28–64% (vs ~7–10% in general female population) | Multifactorial: (1) Cosmetic burden — hirsutism, acne, obesity, alopecia → body image distress → low self-esteem. (2) Infertility distress — especially in cultures where motherhood is central to identity (highly relevant in Hong Kong). (3) Hormonal — androgens and insulin may directly affect neurotransmitter systems (serotonin, dopamine). (4) Chronic disease burden — the knowledge of lifelong metabolic risk is psychologically taxing. (5) Obesity — independently associated with depression. |
| Anxiety | 34–57% | Similar multifactorial mechanisms. Health anxiety about long-term metabolic complications. Social anxiety related to appearance. |
| Eating disorders | Increased prevalence (especially binge eating disorder) | Body dissatisfaction + repeated dieting → disordered eating patterns. Insulin resistance → sugar cravings → binge eating cycle. |
| Reduced quality of life | Significant across all domains | Physical, emotional, and social functioning all impaired. Sexual dysfunction is also reported (related to body image, hirsutism, and partner relationship strain). |
| Impaired body image and self-esteem | Nearly universal | Hirsutism is consistently rated as the most distressing PCOS symptom across cultures. Weight stigma compounds the problem. |
Screen for Psychological Comorbidity
International guidelines explicitly recommend screening for depression, anxiety, and disordered eating at diagnosis and periodically thereafter. Use validated tools (PHQ-9, GAD-7). Addressing psychological wellbeing improves adherence to lifestyle modification, which in turn improves metabolic and reproductive outcomes. Don't neglect the mind when treating the body.
While hirsutism and acne are clinical features of PCOS (already covered), their complications deserve mention:
| Complication | Mechanism |
|---|---|
| Acne scarring (including keloids) | Chronic inflammatory acne → dermal damage → fibrosis → permanent scarring. Keloid formation is more common in certain ethnic groups. |
| Post-inflammatory hyperpigmentation (PIH) | Acne lesions → inflammation → melanocyte stimulation → hyperpigmented macules. More prominent in darker skin types (Fitzpatrick IV–VI). |
| Hidradenitis suppurativa (HS) | Emerging association with PCOS. Both conditions share hyperandrogenism and insulin resistance as pathogenic drivers. HS involves chronic suppurative inflammation of apocrine gland-bearing skin (axillae, groin, inframammary). |
These are iatrogenic complications — important to know for safe prescribing.
| Treatment | Complication | Mechanism / Detail |
|---|---|---|
| COC pills | VTE (DVT/PE), stroke, MI | Oestrogen component → ↑hepatic synthesis of clotting factors (II, VII, IX, X) → hypercoagulable state. Risk is amplified by obesity, smoking, immobilisation, and older age. Risk is ~3–4× higher than non-users. |
| COC pills | Headache, mood changes, breast tenderness, breakthrough bleeding | Hormonal side effects. |
| Spironolactone | Hyperkalaemia, menstrual irregularity, breast tenderness | Aldosterone antagonism → ↑K+ retention. Must monitor K+ especially if co-prescribed with ACEi/ARB. |
| Spironolactone / CPA / Finasteride | Teratogenicity | Anti-androgen effects → feminisation of male fetus. Absolute requirement for effective contraception during use. |
| Metformin | GI upset (nausea, diarrhoea, bloating) | Direct GI irritant effect + altered gut microbiome. Mitigated by slow titration and extended-release formulation. |
| Metformin | Lactic acidosis (rare) | Accumulation if renal impairment → inhibits hepatic lactate metabolism. C/I if eGFR < 30. |
| Isotretinoin (for acne) | Teratogenicity, hepatotoxicity, hypertriglyceridaemia, mucocutaneous dryness, mood disturbance | Must use two forms of contraception. Monitor LFTs and lipids. |
| Gonadotrophins | OHSS, multiple pregnancy | PCOS ovaries are exquisitely FSH-sensitive → multi-follicular development. Use low-dose step-up protocol with intensive monitoring. |
| Letrozole / Clomifene | Multiple pregnancy (lower risk with letrozole), ovarian cyst formation | Over-recruitment of follicles. Letrozole has ~3–5% twin rate (vs ~10% with clomifene). |
| Laparoscopic ovarian drilling | Periovarian adhesions, reduced ovarian reserve | Thermal/mechanical injury → adhesion formation (may paradoxically worsen fertility). Excessive drilling → premature reduction of ovarian reserve. |
High Yield Summary
Complications of PMOS/PCOS span five domains:
1. Reproductive:
- Infertility (anovulatory — leading cause) [3]
- Pregnancy complications: GDM (3×), pre-eclampsia (3–4×), macrosomia, preterm birth, ↑Caesarean section [21][22]
- OHSS during fertility treatment
- Fetal programming → long-term metabolic/CVD risk in offspring [22]
2. Metabolic:
- T2DM (30–40% IGT by age 30; ~10% T2DM) — progression: insulin resistance → IGT → T2DM [3]
- Dyslipidaemia (↑TG, ↓HDL-C, ↑small dense LDL) [3]
- Metabolic syndrome (≥ 3 of 5 criteria) [3]
- NAFLD (hepatic manifestation of metabolic syndrome) [7]
- OSA (5–30× higher prevalence) [3]
3. Cardiovascular:
- HTN, CAD, stroke — driven by metabolic risk factor clustering [3]
- Subclinical atherosclerosis from young age
4. Oncological:
- Endometrial hyperplasia → endometrial carcinoma (2–6× risk) — from chronic unopposed oestrogen [1][12]
- Menstrual regulation: prevent endometrial hyperplasia/CA [1][12]
5. Psychological:
- Depression (28–64%), anxiety (34–57%), eating disorders, poor self-esteem [3]
- Screen at diagnosis and periodically
Active Recall - Complications of PMOS/PCOS
References
[1] Lecture slides: GC 114. Climacteric symptoms menopause and related illness; amenorrhoea.pdf (p28) [3] Senior notes: Ryan Ho Endocrine.pdf (p77, p117) [7] Senior notes: Ryan Ho GI.pdf (p309 — NAFLD) [12] Lecture slides: Block C - Climacteric symptoms_ menopause and related illness; amenorrhoea.pdf (p14) [21] Lecture slides: GC 115. I am pregnant medical problems complicating pregnancy.pdf (p12) [22] Lecture slides: GC 115. I am pregnant medical problems complicating pregnancy.pdf (p13) [23] Lecture slides: GC 115. I am pregnant medical problems complicating pregnancy.pdf (p15) [24] Senior notes: Ryan Ho Endocrine.pdf (p94 — Chronic diabetic complications)
High Yield Summary
Definition: Polyendocrine metabolic ovarian syndrome (PMOS), formerly polycystic ovary syndrome (PCOS) — heterogeneous endocrine/metabolic disorder; diagnosis of exclusion.
Current adult diagnostic criteria (2023 International Guideline) — ≥2 of 3 (after excluding other causes):
- Oligo-/anovulation (cycle >35 days or < 8 cycles/year).
- Clinical or biochemical hyperandrogenism (hirsutism, acne, alopecia; or ↑ free/total testosterone).
- Polycystic ovarian morphology (PCOM) on USS (FNPO >20 per ovary OR ovarian volume ≥10 mL) OR elevated AMH in adults.
2026 Name Update
The 2026 global consensus process renamed PCOS to polyendocrine metabolic ovarian syndrome (PMOS) to avoid implying pathological ovarian cysts and to reflect the condition's endocrine, metabolic, and ovarian features. Implementation is a managed transition, with full integration planned for the 2028 International Guideline update, so expect both PMOS and PCOS in clinical and exam materials during this period.
Epidemiology: 6–20% reproductive-age women; most common endocrine disorder in women; most common cause of anovulatory infertility; most common pathological cause of secondary amenorrhoea in HK.
Pathophysiology — vicious cycle:
- Insulin resistance → hyperinsulinaemia → ↑ ovarian androgen production + ↓SHBG → ↑ free testosterone.
- ↑LH:FSH ratio (classic but not required) → theca cell androgen excess.
- Intra-ovarian hyperandrogenism → arrested follicular development → multiple small subcapsular follicles (PCOM appearance).
- Anovulation → unopposed estrogen → endometrial proliferation.
Clinical features:
- Menstrual: Oligomenorrhoea (most common) or amenorrhoea; anovulatory cycles.
- Hyperandrogenism: Hirsutism (Ferriman-Gallwey ≥8), acne, male-pattern alopecia.
- Metabolic: Obesity (50–80%), acanthosis nigricans, central adiposity.
- NOT virilisation — if rapid virilisation or T >5 nmol/L → androgen-secreting tumour.
Phenotypes (AE-PCOS; legacy PCOS phenotype labels):
- A (classic): All 3 Rotterdam criteria — most common, highest metabolic risk.
- B: Hyperandrogenism + anovulation (no PCOM).
- C: Hyperandrogenism + PCOM (ovulatory PCOS).
- D: Anovulation + PCOM (normoandrogenic).
Risk factors: Family history, obesity, insulin resistance, low birth weight, premature adrenarche.
High Yield Summary — Differential Diagnosis
Mandatory exclusions before diagnosing PMOS/PCOS:
| Condition | Test | Distinguishing features |
|---|---|---|
| Pregnancy | β-hCG | Always first |
| Thyroid dysfunction | TFT | Hypo- or hyperthyroidism |
| Hyperprolactinaemia | PRL | Galactorrhoea, headache |
| Non-classical CAH | 17-OHP (morning, follicular) | ↑17-OHP; may virilise; common in Ashkenazi/Mediterranean |
| Cushing syndrome | 24h UFC / dexamethasone suppression | Central obesity, striae, hypertension |
| Androgen-secreting tumour | Testosterone, DHEAS | Rapid virilisation, T >5 nmol/L, DHEAS >7 μmol/L, ovarian/adrenal mass |
| Drug-induced | History | Valproate, anabolic steroids, danazol |
| FHA | FSH/LH/E2 | ↓FSH/LH/E2, low BMI, stress/exercise |
| POI | FSH (×2) | ↑FSH, hot flushes, age < 40 |
PMOS/PCOS vs other hyperandrogenic states:
| Feature | PMOS/PCOS | CAH | Androgen tumour | Cushing |
|---|---|---|---|---|
| Onset | Gradual (puberty) | Puberty/childhood | Rapid (weeks–months) | Gradual |
| Virilisation | Mild–moderate | Moderate | Severe | Mild |
| Testosterone | Mild ↑ (< 3 nmol/L) | Mild ↑ | >5 nmol/L | Normal/mild ↑ |
| 17-OHP | Normal | ↑↑ | Normal | Normal |
| Ovarian USS | PCOM | Normal | Solid mass | Normal |
PCOM alone is NOT PMOS/PCOS — 20–30% of normal women have PCOM; need ≥2 diagnostic criteria.
PMOS/PCOS vs FHA: PMOS/PCOS has ↑/N androgens, PCOM, often overweight; FHA has ↓gonadotrophins, ↓E2, low BMI, hypothalamic cause.
High Yield Summary — Diagnosis
Diagnostic algorithm:
- β-hCG → exclude pregnancy.
- History: menstrual pattern, hirsutism/acne, weight, family history, drug history.
- Exam: BMI, BP, Ferriman-Gallwey score, acanthosis nigricans, pelvic exam.
- Baseline bloods: FSH, LH, E2, PRL, TFT, total/free testosterone, SHBG, 17-OHP, DHEAS (if virilisation).
- Pelvic USS (TVS) or AMH in adults: FNPO count, ovarian volume, endometrial thickness; AMH is not used for diagnosis in adolescents.
- Metabolic screening: OGTT (75 g — PMOS/PCOS has ↑ GDM/T2DM risk even if non-obese), fasting glucose/HbA1c, lipid profile, LFTs (NAFLD).
Interpretation:
- ↑LH:FSH (>2:1): Suggestive but not required.
- ↑Testosterone: Mild elevation; if >5 nmol/L → tumour workup (USS/MRI adrenals + ovaries).
- ↑17-OHP: Repeat + ACTH stimulation test for CAH.
- ↑DHEAS: Adrenal source (CAH, adrenal tumour).
- Endometrial thickness >4 mm (amenorrhoeic): Consider EA to exclude hyperplasia.
Who needs 17-OHP?: All women with hyperandrogenism + anovulation (especially if non-Caucasian, premature pubarche, severe hirsutism).
Adolescent PMOS/PCOS: Diagnose cautiously because the immature HPO axis can mimic PMOS/PCOS; PCOM and AMH are not recommended for diagnosis in adolescents — rely on hyperandrogenism + persistent ovulatory dysfunction.
Do NOT diagnose PMOS/PCOS solely on USS or AMH — PCOM/AMH is one criterion only, and adolescents require hyperandrogenism + ovulatory dysfunction.
High Yield Summary — Management
Four management domains: (1) Menstrual regulation, (2) Hyperandrogenism, (3) Fertility, (4) Metabolic/long-term health.
All patients — lifestyle first:
- 5–10% weight loss → restores ovulation in ~50–70%; ↓ androgens, ↓ insulin resistance.
- Diet (low GI), exercise ≥150 min/week.
Menstrual regulation (protect endometrium):
- Progestogen withdrawal q1–3 months (medroxyprogesterone 10 mg × 10–14 days) if not seeking contraception.
- COCP — first line if also need contraception/hirsutism; ↓ androgens via ↑SHBG.
- Mirena — if COCP CI or progestogen-only preferred.
Hyperandrogenism (hirsutism):
- COCP first line (↓ ovarian androgens, ↑SHBG).
- Add anti-androgen after 6 months if inadequate: spironolactone 50–200 mg (avoid in pregnancy — feminise male fetus), cyproterone acetate, finasteride.
- Cosmetic: Laser/electrolysis (after 6 months medical Rx — tell patient hirsutism takes ≥6–12 months to improve).
- Do NOT use metformin for hirsutism alone.
Fertility:
- Letrozole 2.5–7.5 mg days 2–6 — first-line ovulation induction (superior to clomiphene in PMOS/PCOS — LIVE study).
- Clomiphene 50–150 mg days 2–6 — second line.
- Metformin alone — NOT first-line for fertility (may add to clomiphene if resistant).
- Gonadotrophins — third line (specialist; OHSS risk).
- IVF — if failed ovulation induction or additional factors (tubal, male).
- Weight loss 5–10% before fertility treatment.
Metabolic management:
- Metformin 500–2000 mg/day — insulin sensitiser; use for IGT/T2DM or failed lifestyle; may aid weight/menstrual regularity but NOT first-line for fertility.
- Screen and treat: dyslipidaemia, hypertension, OSA (STOP-BANG).
Long-term monitoring: Annual BP, glucose/HbA1c, lipids; endometrial protection if amenorrhoeic >3 months.
High Yield Summary — Complications
Reproductive:
- Anovulatory infertility — most common cause of anovulatory subfertility.
- Miscarriage — slightly ↑ (likely related to obesity/insulin resistance).
- Pregnancy complications: GDM (2–4×), pre-eclampsia (3×), preterm birth, LGA (if GDM uncontrolled).
Endometrial:
- Endometrial hyperplasia and cancer (2–6× risk) — unopposed estrogen from anovulation.
- Prevention: Progestogen-induced withdrawal q1–3 months OR continuous progestogen (Mirena/COCP).
- EA if AUB or endometrial thickness >4 mm in amenorrhoeic patient.
Metabolic:
- Type 2 diabetes — 4× risk; 50% have IGT by age 40; screen with OGTT.
- NAFLD/NASH — up to 40%.
- Dyslipidaemia — ↑ triglycerides, ↓ HDL.
- Obstructive sleep apnoea — independent of BMI.
Cardiovascular:
- ↑ MI, stroke, CVD (insulin resistance, dyslipidaemia, inflammation, endothelial dysfunction).
- Metabolic syndrome in ~40%.
Psychological:
- Depression and anxiety (2×) — body image, infertility, hirsutism.
- Eating disorders (overlap with FHA — distinguish).
Long-term cancer (debated/investigational):
- Possible ↑ ovarian and breast cancer — insufficient evidence for screening changes.
Treatment-related:
- Clomiphene: anti-estrogenic cervical mucus/endometrium; multiple pregnancy (8–10%).
- Letrozole: teratogenic — ensure not pregnant; lower multiple pregnancy vs clomiphene.
- Spironolactone: teratogenic — contraception mandatory.
- OHSS (gonadotrophins/IVF).
Key exam points: Always endometrial protection; letrozole > clomiphene; 5–10% weight loss; screen OGTT; exclude tumour if rapid virilisation.
Climacteric Symptoms And Menopause
Menopause is the permanent cessation of menstruation due to loss of ovarian follicular activity, while the climacteric is the transitional period marked by vasomotor, psychological, and urogenital symptoms resulting from declining estrogen levels.
Dysmenorrhea
Dysmenorrhea is painful menstrual cramping, typically caused by excessive prostaglandin-mediated uterine contractions (primary) or underlying pelvic pathology such as endometriosis or fibroids (secondary).