Digestion Q&A by Dr. Lee

Answer:

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Collagenous colitis is a newly-recognized disease of the colon. On sigmoidoscopy or colonoscopy the bowel lining appears to be normal but microscopic examination of biopsies shows inflammation and the presence of a band-like substance called collagen which is a component of scar tissue. We have no evidence that it is caused by an infectious agent, nor does it appear to be related to any known causes of diarrhea. It was first described in 1976, and it is being diagnosed more frequently. The primary symptom of collagenous colitis is a watery diarrhea, but there also may be abdominal pain, mucus in the stool, and, rarely, weight loss. The usual tests for diagnosing the cause of diarrhea are normal, and the diagnosis is made with the microscopic exam of colonic biopsies. The disease may last for years, and may subside with or without treatment.

In some patients, smoking cigarettes or taking medications such as NSAIDs may cause the collagenous colitis.

The treatment of microscopic colitis has not been standardized because there have not been adequate large scale, prospective, placebo controlled treatment trials. The following strategies are safe and may relieve diarrhea in some patients:

• Avoid NSAIDs and cigarettes
• Trial of lactose elimination (just to eliminate the possibility that intolerance to lactose in milk is aggravating the diarrhea)

• Anti-diarrhea agents such as Imodium or Lomotil

• Bismuth subsalicylate such as Pepto-Bismol
• 5-ASA (mesalamine) compounds such as Asacol, Pentasa, or Colazal
• Two recent, controlled trials showed that budesonide (Entocort, a poorly absorbed steroid) is effective in controlling diarrhea in more than 75% of the patients with collagenous colitis, but the diarrhea tends to recur soon after stopping Entocort.

Though data is lacking, some doctors may consider using medications that potently suppress the immune system such as azathioprine and 6-mercaptopurine among patients with severe microscopic colitis that is unresponsive to other treatments.

Thank you for your question.