Many patients complain of weakness. What is the best way to determine the cause of weakness in a given patient?
The first step is to exclude systemic causes of fatigue or weakness, such as cardiopulmonary disease, anemia, hypothyroidism, malignancy, sleep apnea, or depression.
Many of these patients have malaise rather than weakness, and their examination usually fails to reveal true muscle weakness if they give their best effort.
The carefully directed history and physical examination, combined with focused laboratory testing, are usually effective in eliminating these causes of weakness