Gastroenterology - Chronic Diarrhea: By Sylvain Coderre M.D.

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Gastroenterology - Chronic Diarrhea: A Practical Approach to Chronic Diarrhea
Whiteboard Animation Transcript
with Sylvain Coderre, MD
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There are several definitions for diarrhea. The most “scientific” approach is a stool weight over 300g, or stool volume over 300ml, in a 24-hour period. The more practical definition is a stool frequency over 3 times per day, with a loose stool consistency.
There are several approaches to categorizing chronic diarrhea: physiological (osmotic vs secretory), anatomical (small bowel vs large bowel).
However, my preference is to look at this problem in terms of the four most common causes: lactose intolerance, celiac disease, inflammatory bowel disease, and by default irritable bowel syndrome.
Therefore, a very practical approach to this problem is as follows.
• First, exclude chronic infections (most notably Giardia in campers/well water drinkers and clostridium difficile with antibiotics), and medications (especially new ones, metformin being a good example).
• Second, while formal laboratory tests do exist for lactose intolerance, one way to exclude it is a dairy-free trial for 14 days.
• Next, if the patient is still symptomatic, then consider celiac disease by sending a tissue trans-glutaminase level and/or the gold standard test, a gastroscopy with
duodenal biopsy.
• Inflammatory bowel disease is next to be excluded. This requires a history of prototypical symptoms (for ulcerative colitis, bloody diarrhea, for Crohn’s right lower quadrant pain), laboratory work such as findings of anemia, low albumin, elevated c-reactive protein, and finally if it is still considered, a colonoscopy with view of terminal ileum.
• Having excluded the above, most patients (especially without warning symptoms such as bleeding or weight loss) will have diarrhea-predominant irritable bowel syndrome, an entity which may also be accompanied by bloating, abdominal pain relieved by defecation, constipation, and mucus in the stools.
One caveat to the above approach: in older patients, consideration must be given to colon cancer (especially with iron deficiency anemia) and microscopic colitis (especially with use of NSAIDS).