Recurrent fetal thyrotoxicosis in a woman with Graves' disease: case report

The thyroid stimulating immunoglobulins are generally believed to be the cause of hyperthyroidism in Graves' disease. Placental transfer of these antibodies from a mother with autoimmune thyroid disease can result in fetal thyroid disorders. We report the case of a 31-year-old woman who had a history of Graves' disease. She received thyroxine therapy for post thyroidectomy hypothyroidism. Two years after the thyroidectomy, she became pregnant. Unfortunately, intrauterine fetal death occurred in midgestation. One year later, she became pregnant again. In the 26th week of gestation, fetal thyrotoxicosis was diagnosed using clinical pictures, including fetal tachycardia and cardiomegaly, and a hormonal evaluation of a periumbilical blood sampling (T4: 18 micrograms/dl, T3: 65.3 ng/dl, TSH: < 0.03 microU/ml) was performed. Antimicrosomal antibodies were not detectable in either the maternal or fetal blood. In this case, high levels of TBII were detected during pregnancy and crossed the placenta to result in a thyrotoxic fetus in the second pregnancy. We recommend that both the regular monitoring of the thyrotropin receptor antibodies of pregnant women with a history of autoimmune thyroid disease, and routine measurements of the fetal heart rate and intrauterine growth during gestation be mandatory for the early detection of fetal thyroid disorders. Cordocentesis for measuring fetal thyroid function is helpful in reaching a definite diagnosis and for guiding therapy.