Chronic Fatigue Workup

Common, non-specific symptom — but persistent (≥6 weeks) or progressive fatigue warrants evaluation. Distinguish: • Physiological (lifestyle, exercise, stress, sleep deficit). • Pathological — many causes. Differentials by category: • Endocrine: hypothyroidism, diabetes, Addison's, hypogonadism. • Anaemia. • Infection: post-viral, EBV, CMV, hepatitis, TB, HIV, Lyme. • Inflammatory / autoimmune: SLE, RA, vasculitis. • Malignancy. • Cardiac (HF), respiratory (COPD, sleep apnoea), renal, hepatic disease. • Psychiatric: depression, anxiety, somatisation. • Sleep disorders: OSA, insomnia. • Drugs: beta-blockers, antihistamines, opioids, SSRIs, antiepileptics. • Nutritional: B12, vitamin D, iron deficiency. • Fibromyalgia. • Myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) — diagnosis of exclusion.