Congenital hyperthyroidism caused by diaplacental exchange of thyrotropin receptor antibodies

We describe the case of a premature baby, extremely small for date whose mother had an untreated hyperthyroidism during pregnancy. Severe symptoms of connatal hyperthyroidism appeared after a latency period of seven days. As the underlying cause we suggest the placental transmission of thyrotropin-receptor-antibodies (TRAb), which were elevated in the mother and the newborn. Main symptoms in the newborn were tachycardia, tachypnea, sweating and diarrhea.