Thursday, February 15, 2007

Microscopic colitis may be misdiagnosed as diarrhea predominant irritable bowel syndrome if colonoscopy and intestinal biopsies are not done.

Just published from the Mayo Clinic is a study that indicates that there is a significant overlap of the symptoms of IBS and microscopic colitis. In a group of biopsy proven microscopic colitis patients, the authors noted that approximately half had symptoms that would have met diagnostic criteria for irritable bowel syndrome. Symptom-based criteria for diagnosing IBS are not specific enough to rule out microscopic colitis.

They state “patients with suspected diarrhea predominant irritable bowel syndrome should undergo biopsies of the colon to investigate further for possible microscopic colitis if symptoms are not well controlled by antidiarrheal therapy.” The diagnosis is made by intraepithelial lymphocytosis only seen under the microscope when the colon on the surface looks normal. Many doctors don't biopsy the colon when it looks normal despite the patient having a history of diarrhea. Microscopic colitis is a known treatable cause of such symptoms that can only be diagnosed by colon biopsies.

I suggest that the diagnosis of IBS based solely on symptoms without diagnostic testing is inadequate. Without blood tests and intestinal biopsies, Celiac disease, Crohn’s disease and various forms of colitis including microscopic colitis are frequently missed. I believe anyone undergoing colonoscopy or upper endoscopy with symptoms, especially diarrhea, bloating, gas or abdominal pain, should have multiple intestinal biopsies. Inflammation that is the cause of these symptoms is often only seen microscopically.

The earliest intestinal biopsy findings of Celiac disease and microscopic colitis is increased number of lymphocytes per 100 epithelial (intestinal lining) cells. In the colon intraepithelial lymphocytosis is considered diagnostic for microscopic colitis if 20 or more lymphocytes per 100 epithelial cells are found. Interestingly the criteria for abnormal intraepithelial lymphocytosis in Celiac disease has more recently been reduced from 40 IELs per 100 utilized for nearly thirty years to 30 per 100. Even more recent studies have indicated that this should be reduced further to 20-25 per 100 because it is noted that early gluten injury occurs with lower levels of lymphocytes in the intestinal lining and is associated with a favorable response to gluten free diet. Microscopic colitis frequently responds favorably to a gluten-free diet.

Numerous patients have come to me with a diagnosis of IBS for years who I have confirmed to have Celiac disease, microscopic colitis or non-celiac gluten sensitivity. These patients typically respond dramatically to a gluten free diet even in the absence of a diagnosis of Celiac disease. Several of my patients have both Celiac disease and a form of microscopic colitis such as lymphocytic or collagenous colitis.

These patients often have experienced years of unnecessary suffering and many have already developed preventable secondary complications such as osteoporosis, infertility, iron deficiency or autoimmune diseases. Most have lived for years under false conclusion that they had IBS. They are often frustrated that they had been told there was little to nothing that could be done besides taking antidiarrhea and antispasm medications along with a high fiber diet and fiber supplementation. Yet, most noted that they were worse with increase fiber and had complained to their doctors that such agents seem to cause more severe bloating, gas, diarrhea and abdominal pain. Little did they know that increase gluten was making them worse. Don't accept a diagnosis of IBS without adequate diagnostic testing or consideration of a trial of gluten free diet.

Symptomatic overlap between irritable bowel syndrome and microscopic colitis. Limsui et al. Inflamm Bowel Dis Feb 2007;13(2)175-181.

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