Abstract
Diarrhea is exceedingly common and produces high economic burden. Understanding pathophysiologic mechanisms of chronic diarrhea facilitates a rational approach to diagnosis and management. Careful history taking and physical examination can characterize the mechanism of diarrhea and identify causes. In contrast to acute diarrhea, causes of chronic diarrhea are noninfectious, and most common causes in primary care are functional disorders. The first step is to differentiate functional from organic cause by asking about alarm symptoms and performing minimal screening tests. A therapeutic trial, for example, cholestyramine for bile acid malabsorption, is often appropriate, definitive, and highly cost effective without need for further evaluation. Treatment of chronic diarrhea depends on the specific etiology. For many chronic conditions, diarrhea can be controlled by suppression of the underlying mechanism. For functional diarrhea, empirical therapy may be beneficial.