Neonatal hyperthyroidism in infants of mothers previously thyroidectomized due to Graves' disease

Neonatal hyperthyroidism generally arises as a result of active maternal Graves' disease via transplacental passage of thyroid stimulating immunoglobulins (TSI). On occasions, production of these antibodies may continue after thyroid ablation, either surgically or with radioiodine therapy. We present data concerning three patients (two of them twins) whose mothers had previously undergone near-total thyroidectomy prior to conception. Two of the neonates had neonatal hyperthyroidism due to persistence of TSI in the mother, and the third due to relapse of the maternal Graves' disease during pregnancy. We recommend monitoring TSI during pregnancy in mothers with a history of Graves' disease, even if they are in a state of post-surgical hypothyroidism.