Outcome of Three Neonates Born to Two Goitrous Mothers with High Levels of Thyrotropin Receptor Blocking Antibodies at the Singapore General Hospital

Abstract

Objective. We report the thyroid function of 3 neonates born to 2 goitrous mothers with high levels of thyroid binding inhibitory immunoglobulin (TBII) and TSH receptor blocking antibodies (TSBAb). Methodology. A retrospective chart review of 3 neonates born to 2 goitrous mothers managed in a tertiary institution in Singapore. Results. Patient A had a long-standing history of Graves’ disease (GD) but developed spontaneous hypothyroidism during pregnancy. At 32 weeks, she was found to have high levels of TBII and TSBAb. The neonate had mildly elevated TSH levels for 15 weeks but serum thyroxine levels (subclinical hypothyroidism) remained normal without treatment. The patient became pregnant again 3 years later. The second offspring had TBII with strong TSBAb activity during the perinatal period but remained euthyroid. Patient B was diagnosed with primary hypothyroidism at the age of 13. Subsequent tests revealed strong TBII and TSBAb activity. She became pregnant at age 27 and her TBII levels remained > 40IU/L throughout pregnancy. Her offspring was born with an elevated TBII level of 22.6 IU/L (NR 0-1.5) but normal thyroid function. Conclusion. These cases illustrate that high levels of maternal TSBAb need not necessarily result in neonatal hypothyroidism and also suggest that the maternal and fetal thyroidal responses to these antibodies may not be identical