[Improvement of thrombocytopenia with normalization of thyroid function in a patient with Graves disease].

A 39-year-old man was admitted to our hospital because of hyperthyroidism complicated with fever, atrial fibrillation with rapid ventricular response and congestive heart failure. Laboratory data revealed pancytopenia with a white blood cell count of 3360/microl, Hb 9.6 g/dl, and a platelet count of 88000/ul. After initiation of treatment with 30 mg of thiamazole daily, the patient's thyroid function improved but 4 weeks later, thiamazole induced agranulocytosis occurred and the drug was discontinued. After recovery from agranulocytosis, a subtotal thyroidectomy was performed, and the patient's pancytopenia rapidly improved. In this case, hyperthyroidism itself appeared to be closely related to the development of thrombocytopenia.