In this Article

• What is colitis?
• What diseases are not colitis?
• What is microscopic colitis?
• What are the symptoms of microscopic colitis?
• How common is microscopic colitis and who is at risk?
• What causes microscopic colitis?
• How is microscopic colitis diagnosed?
• What is the prognosis of microscopic colitis?
• What is the treatment for microscopic colitis?
• Lymphocytic Colitis Glossary
• Lymphocytic Colitis Index
• Find a local Gastroenterologist in your town

How is microscopic colitis diagnosed?

The diagnosis of microscopic colitis is made by performing biopsies from different regions of the colon during colonoscopy or sigmoidoscopy.

The abnormalities of the colon's lining in microscopic colitis occur in a patchy distribution (areas of normal lining may exist adjacent to areas of abnormal lining). For this reason, multiple biopsies should be taken from several different regions of the colon in order to accurately make a diagnosis. The patchy nature of microscopic colitis also is the reason why flexible sigmoidoscopy often is inadequate in diagnosing the condition because the abnormalities of microscopic colitis may be absent from the sigmoid colon (the colonic segment that is closest to the rectum and is within the reach of a sigmoidoscope) in 30-40% of the patients with microscopic colitis. Thus, biopsies of other regions of the colon accessible only with colonoscopy may be necessary for diagnosing microscopic colitis.

What is the prognosis of microscopic colitis?

The long term prognosis (course) of microscopic colitis is not clear. In approximately two-thirds of the patients with microscopic colitis, the diarrhea resolves spontaneously after several years. The remaining one-third of the patients experience persistent or intermittent diarrhea for many years (possibly indefinitely).

What is the treatment for microscopic 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
• 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.