RESUMO
Hyperthyroidism is one of the most frequent endocrine disorders and its current treatment is based on drugs, surgery and radioactive iodine. Methimazole is the antithyroid drug of choice because of its potency and infrequent side effects, usuaIly mild. This medication is rarely associated with liver toxicity, usually manifested as cholestatic jaundice. Here we report the case of a 33-year-old woman treated at the University Hospital Fundación Santa Fe de Bogota, with hepatotoxicity induced by a methimazole-based treatment for Graves disease. The pruritus and jaundice appeared after three weeks of therapy, viral hepatitis markers were negative, hepatobiliary ultrasonography was normal, and an increase of the levels of alkaline phosphatase, total bilirubin and aminotransferases was found The causal diagnosis of methimazole-induced hepatotoxicity was supported by the results of a liver biopsy. According to the CIOMS scale the score was 10, and the causal relationship of the hepatic adverse reaction by methimazole is highly probable. The clinical course was satisfactory when the medication was suspended, with clinical improvement at 5 days, and normalization of liver tests at 5 weeks. We discuss this case from a diagnostic and therapeutic approach.