Microscopic Colitis

Microscopic colitis is an umbrella term for two conditions, lymphocytic colitis and collagenous colitis.

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Microscopic colitis is a condition characterised by changes within the colonic mucosa which cannot be seen with the “naked eye”  with conventional endoscopic equipment. Biopsy is required to make the diagnosis. Microscopic colitis takes one of two forms, either lymphocytic colitis or collagenous colitis. In lymphocytic colitis the mucosa is infiltrated by an immune cell known as a lymphocyte in numbers which are considerably greater than normal. In collagenous colitis the membrane upon which the epithelium (cells which form the lining of the gut) sit becomes thickened and it is thought this impairs the proper absorption of salt and water.

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Whilst it can occur in men and in young people it typically arises in women in the 5th and 6th decades of life. Approximately ten times as many women appear to be affected compared to men. In a number of individuals microscopic colitis is associated with undiagnosed coeliac disease or with use of certain drugs including metformin, proton pump inhibitors and non steroidal anti-inflammatory drugs amongst others.

Both forms of microscopic colitis usually present with profuse watery diarrhoea. Treatment is similar to that for other forms of inflammatory bowel disease, but in patients in whom a drug is the evident precipitant it should be avoided. Some patients find that simple anti-diarrhoeals are effective in relieving symptoms. Often patients spend long eriods in remission once it has been established, but this is not invariable.