Family medicine

Weight Loss (unintentional)

Unintentional weight loss is a clinically significant involuntary decrease in body weight, typically defined as a loss of more than 5% of baseline body weight over 6 to 12 months, often indicating an underlying medical, psychiatric, or nutritional disorder.

Murtagh Diagnostic Strategy

CategoryDiagnosisKey DiscriminatorCantonese Question / Finding
Probability DiagnosisNew / poorly controlled DM3Ps: polyuria, polydipsia, polyphagia + weight loss [2]「有冇成日口渴、去好多次廁所、食好多嘢但仲係瘦?」
HyperthyroidismWeight loss + ↑appetite, heat intolerance, tremor, tachycardia [3]「怕唔怕熱?心跳快唔快?手有冇震?」
Depression / psychologicalLow mood, anhedonia, ↓appetite, sleep disturbance「最近心情點?有冇覺得咩都冇意思?」
Serious Not To MissMalignancy (GI, lung, lymphoma)Constitutional Sx (fever, night sweats), mass, haemoptysis, PR bleeding, lymphadenopathy「有冇夜晚出汗、痰有血、大便有血?有冇摸到頸或者腋下有粒嘢?」
TBChronic cough, night sweats, haemoptysis, contact history, immigrant「有冇接觸過肺癆病人?」PE: apical crackles
HIV/AIDSRisk behaviours, recurrent infections, oral thrush「有冇高危性行為或者共用針嘴?」
PitfallsChronic pancreatitisEpigastric pain radiating to back, steatorrhoea, alcohol history [6]「有冇肚痛㩒到背脊?大便有冇好油好臭?」
Coeliac disease / malabsorptionChronic diarrhoea, steatorrhoea, bloating, iron/folate deficiency「有冇成日肚瀉、肚脹?」
CKDFatigue, nocturia, poor appetite [7]「夜晚要唔要起身去廁所?有冇覺得好攰?」
MasqueradesDepressionLow mood, anhedonia, poor sleep, guilt, poor concentration「情緒低落?冇胃口?」
DM (as above)3Ps, FHx, obesity/acanthosis血糖檢查
Drugs (polypharmacy)New medication temporal association「最近有冇轉藥或者加新藥?」
AnaemiaPallor, fatigue, ↓exercise tolerancePE: conjunctival pallor
Trying to Tell Me Something?Cancer phobia / health anxietyRelative recently diagnosed with cancer; excessive worry「你最擔心啲咩?屋企人最近有冇人病?」
Eating disorderBody image distortion, purging, excessive exercise「你覺得自己肥唔肥?有冇催吐?」
Social isolation / elder neglectLives alone, nobody cooking, financial difficulty「平時邊個煮飯畀你食?經濟上有冇困難?」

Case Report Form Answer Builder

Exam Discriminators and Traps

Top Traps That Lose Marks

  1. Forgetting to quantify: Always ask how many kg/lbs and over what time period. ≥5% in 6–12 months = clinically significant.
  2. Not asking if intentional: The entire approach changes if the patient was deliberately dieting.
  3. Missing appetite status: Weight loss with ↑appetite (DM, hyperthyroid) vs ↓appetite (malignancy, depression, CKD) is the key branch point.
  4. Skipping ICE: ICE is a scored CRF field. The hidden concern in weight loss is almost always cancer fear.
  5. Not screening for depression: Depression is the classic masquerade — easy to forget when focused on organic causes.
  6. Forgetting drug history: GLP-1 receptor agonists, metformin, thyroxine, stimulants, laxative abuse → iatrogenic weight loss.
  7. Overlooking elderly frailty: In older patients, unintentional weight loss is one of the 5 criteria of the Fried frailty phenotype [5].

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