An unusual method of diagnosing a common disease.

A 34-year-old woman presented with non-bloody diarrhoea of 14 days duration and vomiting. Physical examination was unremarkable. She had hypokalaemia and metabolic acidosis. Stool studies were negative for Clostridium difficile toxin, faecal leucocytes and parasites. Colon appeared normal on colonoscopy. Pronounced scalloping of ileal folds was noted on ileoscopy. Ileal biopsies revealed villous blunting, crypt hyperplasia, marked intraepithelial lymphocytosis and lymphocytic infiltration of the lamina propria, consistent with lymphocytic ileitis in coeliac disease. Serology revealed elevated antitissue transglutaminase IgA antibodies (>100 U/ml). Institution of a strict gluten free diet resulted in complete resolution of symptoms. Although rare, coeliac disease can present as an acute diarrhoeal illness and should be considered after infectious aetiologies are excluded.