Weight loss

Unintentional weight loss. 5% weight loss is considered significant. More precisely, weight loss is clinically important if it exceeds 5% of body weight or 5kg over 6 months — though this doesn’t distinguish loss of lean mass from fat mass, and fluid accumulation (heart failure, chronic kidney disease) can mask a clinically important loss of lean body mass on the scale.

Red flags

Fever, night sweats or generalised lymphadenopathy; bone pain; dyspnoea, cough or haemoptysis; polydipsia and polyuria; and headache, jaw claudication or visual disturbance in an older adult (giant cell arteritis). When a patient’s chronic disease has been stable, don’t assume it explains a new, acute weight loss — a stable condition can mask a new, unrelated diagnosis.

Differential (Murtagh)

• Probability: stress/anxiety, depressive illness, non-coping elderly/ dementia, eating disorders (anorexia nervosa/bulimia).
• Serious, not to miss: chronic congestive heart failure; malignancy (stomach, pancreas, lung, caecum, lymphoma, myeloma — weight loss may be the only sign); chronic infection (HIV, TB, hidden abscess, infective endocarditis, brucellosis).
• Often missed: drug/alcohol dependence, malabsorption (coeliac disease, intestinal parasites), other GI disease, chronic kidney failure, connective tissue disease (SLE, RA). Rarities: malnutrition, Addison’s disease, hypopituitarism.
• Seven masquerades: depression, diabetes (type 1), drugs (digoxin, cytotoxics, NSAIDs, theophylline, stimulants), anaemia, thyroid disorder (hyperthyroidism), UTI.
• Other drug causes to check: SSRIs, topiramate, zonisamide, metformin, levodopa, and the GLP-1 agonists (exenatide, liraglutide) now widely prescribed for diabetes and obesity — an intended effect there, but still worth confirming it’s not unintentional or excessive.
• In older adults specifically, work through a “D” checklist: dentition, dementia, depression, diarrhoea, disorders (severe renal/cardiac/pulmonary), drugs, dysfunction, dysgeusia, dysphagia — multiple factors often contribute at once rather than a single cause, and social isolation/loss of a partner or ability to prepare meals is a common, easily-missed contributor.

Assessment

• History — quantify the amount and time course. Appetite: diminished in psychogenic causes and most cancers; increased in endocrine causes (e.g. hyperthyroidism, diabetes) and some cancers. A patient’s own report of weight loss can be inaccurate — corroborate with old records, changed clothing size, or a family member’s account where possible.
• Examination — BMI, BP, HR; palpate the thyroid for a goitre; abdominal exam (liver, masses, tenderness); reflexes (brisk in hyperthyroidism); dental acid erosion (bulimia).
• Investigations — basic panel: FBC, UEC, ESR/CRP, TFTs, glucose, urinalysis, FOBT, CXR. Consider: gastroscopy/colonoscopy, HIV serology, abdominal ultrasound, LFTs, tumour markers (CA-125, CEA). If the full history, examination and this panel are unremarkable, extensive imaging (CT/MRI) is not recommended — it is low-yield and can mislead with incidental findings; instead arrange dietician input and review with a weight check in about a month.