Chronic diarrhea newly appreciated syndromes

A 60-year-old woman with a three-year history of watery diarrhea had undergone several extensive workups before the diagnosis of a relatively new syndrome, collagenous colitis, was made. One lesson is that in patients with unexplained diarrhea, normal-appearing sigmoid or colon mucosa should always be biopsied. Collagenous colitis is most common in middle-aged women, but we have seen collagenous and microscopic (lymphocytic) colitis in patients in their 30s and in men as well as in women. Another lesson is to beware of features that do not fit comfortably with a diagnosis of irritable bowel syndrome, such as nocturnal diarrhea, malabsorption, or onset in the elderly. Understanding the importance of secretagogues such as lactose, fructose, sorbitol, caffeine, and fat can help in the management of any diarrheal disorder.