- Diabetes mellitus – Patients usually present with polyuria (urinate a lot), polydipsia (drink a lot) and polyphagia (eat a lot). The patients usually has a concurrent weight loss.
- Hypothyroidism – fatigue is a prominent features apart of other symptoms like weight gain, cold intolerance dry skin, constipation and menstrual irregularities
- Drugs – beta blockers, reserpine, diuretics (mainly due to hypokalemia), antihistamine, antidepressants, tranquilizers, steroids, narcotics, alcohol, etc
- Chronic sleep deprivation
- Congestive heart failure – fatigue in this patients indicated reduce cardiac output.
- Occult infection
- Iron deficiency anemia
- Obstructive sleep apnea – excessive daytime somnolence
- Renal failure
- Chronic fatigue syndrome – the fatigue lasting longer than 6 months duration. The affected person usually has less than 50% reduction of their physical capacity.
- Cushing syndrome
- Occult cancer – common cancers associated with fatigue are leukemia, lymphoma and pancreatic cancer. The patients usually also have adenopathy, lymphadenopathy and night sweats.
- Addison disease
- Myasthenia gravis – early stage of illness involves the cranial muscles lead to ptosis, diplopia and chewing fatigue. Muscle weakness exacerbated by repeated use.
- Infectious mononucleosis – acute onset of prominent fatigue
- Depression – patients usually have symptoms of fatigue, sleep disturbance, anorexia and anhedonia (loss interest of any activity)
- Panic disorder
- Somatization disorder
Reference:
- Murray Longmore et al. Oxford Handbook of Clinical Medicine. 7th edition.
- David S. Smith et al. Field Guide to Bedside diagnosis. 2nd edition. 2007. Lippincott Williams and Wilkins.
- Tao Le et al. First Aid for the Family Medicine Boards. McGraw Hill. 2008.

