Cholestasis secondary to hyperthyroidism made worse by methimazole

A 28-year-old man presented with weight loss, jaundice, and pruritus. This was diagnosed to be secondary to Graves disease and the patient was prescribed methimazole. He returned 2 weeks later with worsening of his jaundice. Further investigation, including liver biopsy, indicated that there was superimposed methimazole-induced cholestasis. Discontinuation of methimazole and treatment of hyperthyroidism with lithium followed by radioactive iodine therapy resulted in resolution of his symptoms. This case highlights the fact that worsening cholestasis after therapy for Graves disease should raise the possibility of thionamide-induced exaggeration of liver cholestasis.