SUN-517 Methimazole-Induced Neutropenia in Premature Twins with Graves’ Disease

Introduction: Neonatal Graves’ disease (NGD) occurs in approximately 1-5% of infants born to women with Graves’ disease. It is caused by trans-placental crossing of thyroid stimulating immunoglobulin (TSI) antibodies during third trimester. Hyperthyroidism during pregnancy can lead to craniosynostosis, goiter, premature bone maturation, developmental delay or even heart failure in the neonate. Neonatal Hyperthyroidism is usually transient and resolves in few weeks. Treatment consists of beta blockers and Methimazole. Studies in adults recommend discontinuing of Methimazole if patients develop neutropenia. However due to lack of alternatives, we present a case of continued use of Methimazole with neutropenia in newborn twins. Case Report: 33 weeks gestational age mono-chorionic/di-amniotic twins born to a 34-year-old woman with poorly controlled hyperthyroidism. Mother diagnosed with Graves’ disease during 2nd trimester with poor control throughout pregnancy. At the time of delivery, maternal TSH was