Concomitant Agranulocytosis and Hepatotoxicity after Treatment with Carbimazole

Objective:To describe a case of agranulocytosis and severe hepatotoxicity associated with Carbimazole treatment.Case Summary:A 37-year-old woman was diagnosed with severe hyperthyroidism resulting from Graves' disease. Treatment with Carbimazole 30 mg/day was initiated. Within 15 days following the start of therapy, both minor (eg, pruritus, rash, urticaria, fever, arthralgias) and potentially life-threatening (eg, agranulocytosis, severe mixed hepatotoxicity with severe cholestatic jaundice) adverse effects developed. The patient's symptoms and laboratory abnormalities resolved following withdrawal of Carbimazole. Treatment with other antithyroid drugs was not attempted, and 131I ablation of the thyroid was successfully performed. Thyroid function was maintained with standard follow-up care. Agranulocytosis, identified following bone marrow biopsy, was treated with granulocyte colony-stimulating factor.Discussion:Agranulocytosis and hepatotoxicity are rare adverse effects associated with Carbimazole trea...