RESUMO
High titer of maternal thyroid-stimulating hormone receptor antibody (TRAb) in patients with Graves' disease could cause fetal hyperthyroidism during pregnancy. Clinical features of fetal hyperthyroidism include tachycardia, goiter, growth restriction, advanced bone maturation, cardiomegaly, and fetal death. The recognition and treatment of fetal hyperthyroidism are believed to be important to optimize growth and intellectual development in affected fetuses. We herein report a case of fetal treatment in two successive siblings showing in utero hyperthyroid status in a woman with a history of ablative treatment for Graves' disease. The fetuses were considered in hyperthyroid status based on high levels of maternal TRAb, a goiter, and persistent tachycardia. In particular, cardiac failure was observed in the second fetus. With intrauterine treatment using potassium iodine and propylthiouracil, fetal cardiac function improved. A high level of TRAb was detected in the both neonates. To the best of our knowledge, this is the first report on the changes of fetal cardiac function in response to fetal treatment in two siblings showing in utero hyperthyroid status. This case report illustrates the impact of prenatal medication via the maternal circulation for fetal hyperthyroidism and cardiac failure.