Clinical Dimensions of Fatigue.

Because the symptom of fatigue is often vague, clinical evaluation requires the consideration of distinct features such as timing, precipitants, presence of libido, sleep quality, exercise capacity, and sedation. Fatigue has dimensions of affect and tolerability. In chronic illness, it is helpful to consider mood, physical conditioning, course of predictable treatment consequences, postural hypotension, and the well-being of caretakers. The differential diagnosis of acute and chronic fatigue is considered. Chronic fatigue of unknown etiology is placed in historical context, and an approach to the complexities of providing continuing evaluation and care is discussed.