Chronic Diarrhea

Differential Diagnosis of Chronic Diarrhea
The differential diagnosis of chronic diarrhea (i.e., diarrhea lasting at least 4 to 6 weeks) includes chronic and relapsing gastrointestinal infection, inflammatory bowel disease, microscopic colitis, malabsorption syndromes, medication side effects, endocrine disorders, laxative abuse, colonic neoplasia, and idiopathic (functional) diarrhea, as well as neuroendocrine tumors. Guidelines recommend using the history and the findings on physical examination plus laboratory testing to categorize chronic diarrhea as secretory, osmotic, inflammatory, or fatty; this categorization can narrow the differential diagnosis and guide further testing.

What red-flag signs should not be missed in patients with chronic diarrhea?
A: In patients with chronic diarrhea, so-called alarm or red-flag signs include weight loss, nocturnal symptoms, a family history of colorectal cancer, rectal bleeding, or anemia; any of these signs and symptoms would warrant further evaluation.

In a patient with chronic diarrhea, what features might distinguish an organic versus a functional cause (such as irritable bowel syndrome)?
A: Historical features that suggest an organic as opposed to a functional cause of chronic diarrhea, such as irritable bowel syndrome, include a shorter duration of diarrhea (less than 3 months), nocturnal diarrhea, an abrupt onset of diarrhea, weight loss of more than 11 lb (5.0 kg), and stool weight of more than 400 g per day. Common causes of chronic diarrhea include the irritable bowel syndrome, inflammatory bowel disease, malabsorption syndromes, and chronic infections, particularly in patents who are immunocompromised.

What disorder involving the small bowel is associated with Graves' disease?
A: Celiac disease is common among patients with Graves' disease.

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New England Journal of Medicine - Vol. 360, No. 6, February 5, 2009