Hyperthyroidism in a premature baby due to transplacental passage of maternal thyrotropin-receptor-antibodies

The duration of the stimulating effect of transplacental transferred thy ro tropin-receptor-antibodies (TRAb) is discussed by the example of a 23 years old woman suffering from Graves' disease with a severe hyperthyroidism. Sh e became pregnant six weeks after the diagnosis was obtained and then disco ntinued her antithyroid medication on her own responsibility. On a check-up in the 20th week of pregnancy, a hyperthyroidism was once more found, lead ing to a therapy with propylthiouracil, which however, was again interrupte d by the patient a few weeks later In the 32th week, she gave birth to a ma le child that already presented with distinct signs of thyrotoxicosis and d eveloped a continuous deterioration of the condition, including a tachycard ia with up to 190 beats per minute, fever, tremor and a respiratory disorde r. Assay of the newborn serum revealed a severe hyperthyroidism. The TRAb l evel was 180 U/l (normal range <15). A therapy with propranolol and prednis olon was initiated, leading to a significant improvement of the general con dition. Nevertheless, after 12 days, there was still no notable decrease of the hormone levels. Therefore an antithyroid medicatjon was started, which caused normal thyroid hormone levels within 9 days. However, after the the rapy was stopped, a hyperthyroidism was again observed within one week, req uiring 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.