Falsely elevated anti-tissue transglutaminase antibodies in patients with immunoproliferative small intestinal diseases: A case series.

Immunoproliferative small intestinal disease (IPSID) is an uncommon disease of the small intestine. There is a similarity in the clinical presentations of enteropathic diseases, including celiac disease, tropical sprue, IPSID, and Whipple's disease. A differentiation between them is based on the use of a highly specific serological test for celiac disease and specific histological characteristics. We found that IgA-anti-tissue transglutaminase antibody (IgA-tTG Ab) is falsely elevated in a subset of patients with IPSID. The levels of IgA-tTG Ab fall with the treatment of IPSID. The healthcare professional should be aware of the conditions that lead to a false-positive anti-tTG Ab. Intestinal mucosal biopsies even in the presence of anti-tTG Ab should be done in endemic regions as they provide an opportunity for making a diagnosis of alternative and uncommon diseases before the diagnosis of celiac disease.