Graves’ disease overlapping with chronic hepatitis B and methimazole-induced liver injury and autoimmune hepatitis: a case report

Background Liver injury related to Graves’ Disease (GD) includes hepatotoxicity of thyroid hormone excess, drug-induced liver injury, and changes resulting from concomitant liver disease. Methimazole (MMI) has been shown to induce several patterns of liver injury. However, the diagnosis and treatment of autoimmune hepatitis (AIH) overlapping with either GD or chronic hepatitis B are challenging. Case presentation A 35-year-old man from China presented with a two-year history of GD and a 10-day history of progressive jaundice. He had taken MMI for two months and discontinuing treatment due to liver toxicity 1 year ago and for another 6 days 20 days prior to hospitalization. The patient was diagnosed with GD overlapping with chronic hepatitis B and MMI-induced liver injury with early stage of acute-on-chronic liver failure on admission. However, the elevated aminotransferase and bilirubin levels could not be controlled after correction of liver failure and effective control of HBV replication and hyperthyroidism by daily oral entecavir and one-time oral administration of 131-iodine. The patient underwent liver biopsy on the 43rd day of hospitalization, showing HBsAg expression on the membrane of hepatocytes and typical histopathological characteristics of AIH. He was finally diagnosed with GD overlapping with chronic hepatitis B and MMI-induced liver injury and AIH. The elevated aminotransferase and bilirubin completely returned to normal by 3-month glucocorticoid therapy and continuous entecavir treatment and there was no recurrence during a 6-month follow-up, suggesting that AIH in this patient is different from classical AIH or GD-associated AIH. Conclusions GD together with AIH is a complex and difficult subject. It needs to be clarified whether MMI or HBV can act as a trigger for AIH in this patient.