Hemolytic Anemia Associated with Methimazole Treatment for Graves’ Disease

Methimazole is the most frequently used antithyroid drug for the treatment of thyrotoxicosis in Europe. Haematological side effects of Methimazole such as agranulocytosis, aplastic anaemia and thrombocytopenia are well known, but haemolytic anaemia was very seldom reported. A 51 years old Caucasian man presented with severe Graves’ disease. After 2 weeks of Methimazole treatment (30 mg/day), the patient developed pruritus and arthralgia; biochemical data showed haemolytic anaemia with increased reticulocytes, total and unconjugated bilirubin. Methimazole was replaced by carbimazole and then replaced by lithium carbonate (450  600 mg/day), with normalization of thyroid hormones levels. Intravenous glucocorticoids (Methylprednisolone 125 mg/day, 3 days) followed by oral corticosteroids (Prednisone 1 mg/kg bw/day) and folic acid 5 mg/day successfully controlled haemolytic anaemia. Total thyroidectomy was safely performed and the patient had an uneventful recovery. This is the first case report of haemolytic anaemia associated with Methimazole in Romania. It should be underlined that haemolytic anaemia could be associated with Graves’ disease and may be a rare complication associated with methimazole therapy.