[Recovery from pancytopenia and liver dysfunction after administration of thiamazole for hyperthyroidism]

A 45-year-old woman was referred to our hospital because of hyperthyroidism complicated by atrial fibrillation and heart failure. Laboratory data revealed pancytopenia, with a white blood cell count of 2,600/microliter, red blood cell count of 330 x 10(4)/microliter, and platelet count of 6.2 x 10(4)/microliter. The patient had normal transaminase levels, but tests for hepaplastin and cholinesterase showed values of 34% and 1.4 U/ml, respectively, indicating liver dysfunction. There was also decreased excretion of indocyanine green. After initiation of treatment with 30 mg thiamazole and 20 mg propranolol daily, the patient's thyroid function normalized and the other abnormal laboratory findings such as pancytopenia and liver dysfunction also disappeared. Pancytopenia is a rare complication of hyperthyroidism. In this case, various laboratory abnormalities were normalized by antithyroid therapy alone, indicating that the hyperthyroidism itself was closely related to the pathogenesis of pancytopenia and liver dysfunction.