Frequent causes of fatigue and suggested first-line assessment
| Common causes of fatigue | First-line assessment | |
| Drug-induced fatigue | Steroids, anti-arrhythmic, anti-hypertensive, benzodiazepines or other antidepressant and sedative agents, anti-histaminic, diuretics | Medication review |
| Pregnancy | β-HCG | |
| Anaemia | Iron or vitamin deficiencies | C-reactive protein, haemoglobin, Coombs test, ferritin, B9 and B12 vitamins |
| Metabolic disorders | Hypothyroidism, adrenal insufficiency, panhypopituitarism | TSH, fasting glucose… |
| Vitamin D insufficiency | Vitamin D levels | |
| Infection | Chronic bacterial (mycobacterial) or viral (HIV, hepatitis B and C, EBV) infections | C reactive protein Hepatitis B/C, EBV and HIV serology Quantiferon |
| Organ failure | Cardiac insufficiency Respiratory insufficiency Liver insufficiency Kidney insufficiency | BNP, chest X-ray, echocardiography creatinine, full hepatic tests |
| Sleep disorders | Obstructive sleep apnoea syndrome Jet lag syndrome in frequent travellers | Polysomnography |
b-HCG, b-human chorionic gonadotropin hormone; BNP, brain natriuretic peptide; EBV, Epstein-Barr virus; TSH, thyroid-stimulating hormone.