[Lymphocytic colitis: hypopotassemia as a complication and an association with toxic multinodular goiter]

Lymphocytic colitis is a rare clinicopathologic syndrome, characterized by chronic watery diarrhea, diffuse inflammatory changes in the colonic mucous in spite of normal findings on colonoscopy and marked intraepithelial lymphocytic infiltration on biopsy. Although the physiological mechanism of diarrhea is not clear, patients do not usually present hydroelectrolytic alterations and the results of routine laboratory investigations are usually normal. The association between lymphocytic colitis and thyroid disease, possibly autoimmune, in the form of hypo- or hyperthyroidism is relatively common. We report a 61-year-old woman with a history of multinodular toxic goiter, whose previously uninvestigated chronic diarrhea became more acute and led to the diagnosis of lymphocytic colitis. Results of laboratory investigations revealed only a significant hypokalemia with an associated nonfunctioning bilateral adrenal incidentaloma. The patient evolved well when treated with sulfasalazine. Hypokalemia as a complication of lymphocytic colitis and an association between lymphocytic colitis and toxic multinodular goiter does not seem to have been previously described.