Delayed cholestatic hepatitis due to methimazole

We report on a 71-year-old man who presented to the medical department of Our Lady of Maryknoll Hospital with progressive cholestatic hepatitis. Tests for hepatitis viral markers gave negative results and ultrasonography revealed no dilated bile ducts. Endoscopic retrograde cholangiopancreatography showed a normal biliary tree. The patient had completed a 5-month course of methimazole to treat thyrotoxicosis a few weeks before the onset of the jaundice. Methimazole was suspected to be the cause of the cholestatic hepatitis; this diagnosis was supported by the results from a liver biopsy. The presentation of the patient was unusual by virtue of the delayed onset and prolonged course of cholestasis.