[Thyrotoxicosis after cord blood transplantation for acute myelogenous leukemia].

We describe a 44-year-old man with acute myelogenous leukemia who developed thyrotoxicosis after unrelated cord blood transplantation. He complained of fever, general fatigue, tremor and tachycardia on day 63. On examination of thyroid function, free triiodothyronine (23.67 pg/ml) and free thyroxine (5.71 ng/dl) were increased, and thyroid-stimulating hormone (<0.03 microU/ml) was decreased. Antithyroid receptor antibody, antithyroid peroxidase antibody and antithyroglobulin antibody were all negative. The patient was diagnosed as having thyrotoxicosis. His symptoms improved and thyroid function returned to the normal levels within 2 weeks. Thyrotoxicosis is a rare complication, but we should be aware that it may cause idiopathic fever after stem cell transplantation.