This is a form of colitis that causes chronic, watery diarrhea. The colon/large intestine looks normal when viewed with imaging or a colonoscopy, but biopsies (tissues samples that are examined under a microscope) show inflammation on a cellular level. There are two different types of microscopic colitis that have been established, lymphocytic and collagenous. If you have one of these disorders, there is no evidence that your life span will be shortened or have severe problems.
Microscopic colitis typically occurs in middle-aged or elderly patients, but it can affect anyone. Women are more commonly affected. Some studies say that microscopic colitis is more common in people with celiac disease, irritable bowel syndrome, and thyroid disease.
Normally, in the colon there is a collagenous band in the tissue that is 1-7 micrometers in thickness; in collagenous colitis it ranges from 7-100 micrometers. Collagen is a fiber the body produces that is present in connective tissue. In lymphocytic colitis, there is no thickening of this collagen band, but rather extra inflammatory cells (lymphocytes) present in the colon tissue.
Mainly, the colon is affected but the last part of the small intestine, the terminal ileum, can also have changes. Sometimes, there is overlap in these disorders; they may, or may not, be related but bring about similar symptoms. Why these abnormalities develop is unknown; there are several theories. With collagenous colitis perhaps the breakdown or the production of collagen is inappropriate or a toxin from bacteria causes injury to the colon lining. Medications may have a role in the development; specifically associated medications are listed in the table below. The diarrhea in this disorder is not related to the thickness of the collagen but mimics the severity of the inflammatory changes in the colon tissue so the loose stools are likely related to inflammation.
Nonbloody chronic watery diarrhea, up to 2 liters
Based on your symptoms, a colonoscopy may be performed, and just like the name implies, the diagnosis of MICROSCOPIC colitis is made with a microscope with a biopsy of the colon.
If microscopic colitis is thought to be drug-induced, clearly that medicine will be stopped. Often the diarrhea will resolve within weeks with, or without, treatment but the return of symptoms is common, happening in 30-60% of people.
If with stopping any triggering medicines, treating celiac disease or irritable bowel syndrome you continue to have symptoms, and antidiarrheal medicine like loperamide may be effective. If no benefit is seen, the following steps can be taken:
Budesonide (Entocort)
This is a steroid, similar to prednisone, which decreases inflammation and the activity of the immune system. It acts more locally within the colon without the widespread side effects of prednisone because of how it is broken down in the liver. One study showed that 60% of patients improved within 2 weeks, and 85% in 4-6 weeks in patients with collagenous colitis.
Aminosalicylates may be tried.
The specific mechanism of mesalamine is unknown, but is it thought that it decreases the local inflammatory response right at tissue that is irritated.
There may be an association with gluten sensitivity and microscopic colitis, so even if you have not been diagnosed with celiac disease, but you are not responding to any of the above medications, a trial of a gluten-free diet may be attempted.
| Collagenouscolitis | Lymphocyticcolitis | Possibilities |
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It is suggested to substitute or discontinue |
If you’re experiencing any of the above symptoms of microscopic colitis, call our gastroenterology offices at (715) 847-2558.
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