Half of all patients presenting with fatigue have a psychological cause. Patients with a history of anxiety or depression or those with a duration of symptoms for more than 3 months are more likely to remain symptomatic 6 months later. Physicians should perform a physical examination, take a thorough history, and screen patients for depression using a validated primary care instrument, such as the Beck Depression Inventory or Prime-MD. Physicians may also consider a directed laboratory evaluation with sedimentation rate, blood count, and glycohemoglobin and thyroid stimulating hormone (TSH) levels, particularly in older patients. Grade of Recommendation: C, based on case series and expert opinio
