[Hyperthyroidism in a premature infant due to transplacental passage of maternal thyrotropin receptor antibodies].

The duration of the stimulating effect of transplacental transferred thyrotropin-receptor-antibodies (TRAb) is discussed by the example of a 23 years old woman suffering from Graves' disease with a severe hyperthyroidism. She became pregnant six weeks after the diagnosis was obtained and then discontinued her antithyroid medication on her own responsibility. On a check-up in the 20th week of pregnancy, a hyperthyroidism was once more found, leading to a therapy with propylthiouracil, which however, was again interrupted by the patient a few weeks later. In the 32nd week, she gave birth to a male child that already presented with distinct signs of thyrotoxicosis and developed a continuous deterioration of the condition, including a tachycardia with up to 190 beats per minute, fever, tremor and a respiratory disorder. Assay of the newborn serum revealed a severe hyperthyroidism. The TRAb level was 180 U/l (normal range < 15). A therapy with propranolol and prednisolone was initiated, leading to a significant improvement of the general condition. Nevertheless, after 12 days, there was still no notable decrease of the hormone levels. Therefore an antithyroid medication was started, which caused normal thyroid hormone levels within 9 days. However, after the therapy was stopped, a hyperthyroidism was again observed within one week, requiring another, low-dose antithyroid medication, which was administered for 26 days. After this period, the TRAb level was down to 25 U/l and no more hyperthyroidism was found. The biological half-life of the TRAb was 20 days in our case.