Neonatal thyrotoxicosis with maternal hypothyroidism.

Neonatal Graves' is uncommon, but a potentially fatal condition caused by transplacental transfer of thyroid stimulating immunoglobulin (TSI). It is seen in 1%-5% of infants born to a mother with Graves' disease. Here, we report a unique case of transient neonatal thyrotoxicosis with positive TSI in a premature neonate born to the mother with primary hypothyroidism. A short course of antithyroid drug treatment leads to significant clinical and biochemical improvement followed by complete recovery.