A Case of Transient Neonatal Hypothyroidism Due to Maternal TSH-Binding Inhibitor Immunoglobulins

Kim, Shung Shin; Song, Moon Young; Shu, Byung Kyu; Lee, Byung Churl

Abstract

Recognition of transient forms of neonatal hypothyroidism is very important to prevent the complications of congenital hypothyroidism. Transplacental passage of TSH-binding inhibitory immunoglobulins(TBII) may result in transient congenital hypothyroidism. Transient neonatal hypothyroidism was found in a daughter of 25-yr-old mother who was receiving levothyroxine for primary hypothyroidism due to Hashimoto's thyroiditis. The neonate was treated with thyroxine which was discontinued at 24 months of age. Thyroid scanning during the neonatal period failed to identify functional thyroid tissue, suggesting thyroid agenesis, whereas thyroid scan performed on subsequent follow-up revealed a normal gland. Sequential measurements of serum autoantibodies directed towards the TSH receptor were made in the patient and her mother. High titers of blocking antibodies were present in the mother(TBII, 82.1%) and newborn(TBII, 85.5%) at 19 days after birth. The levels remained persistently high in the mother, whereas they declined and undetectable in the patient at 23 months of age. The above laboratory and clinical data were compatible with blocking nature of TBII, resulting in transient neonatal hypothyroidism and an athyreotic appearance on scan. The TBII measurement can be a useful predictor of neonatal hypothyroidism as well as confirming the nature of the disease in newborn.