Acute cholestatic hepatitis along with agranulocytosis: A rare side effect of carbimazole

Antithyroid drugs have been used for more than 50 years for the management of hyperthyroidism. Most patients tolerate treatment well but some may develop life-threatening side effects such as agranulocytosis, aplastic anemia and cholestatic hepatitis. A 45-year-old female was diagnosed with severe hyperthyroidism. Treatment with Carbimazole 30 mg/day was initiated. Within six weeks following the start of therapy, patient developed potentially life-threatening acute cholestatic hepatitis and agranulocytosis as adverse effects to carbimazole. The patient's symptoms and laboratory abnormalities resolved following withdrawal of offending drug. Agranulocytosis and cholestatic hepatitis together is an extremely rare idiosyncratic side effect of Carbimazole treatment and considered to be dose and age-related. Antithyroid drugs are deceptively easy to use, but because of the variability in the response of patients and the potentially serious side effects, all practitioners who prescribe the drugs need to have a working knowledge of their complex pharmacology.