High maternal serum thyroid-stimulating hormone receptor antibodies with fetal and neonatal thyrotoxicosis after total thyroidectomy for Graves' disease.

High thyroid-stimulating hormone receptor antibodies (TSHRAbs) during pregnancy pose clinical challenges, especially for women with a history of thyroidectomy or radioactive iodine therapy. We report a pregnant woman in her 30s with a history of Graves' disease, managed by total thyroidectomy and thyroid replacement therapy 10 years before presentation. Despite lacking a thyroid gland, she had elevated levels of TSHRAb early in her pregnancy. The fetus experienced early-onset intrauterine growth restriction; at 31 weeks gestation, demonstrated signs of thyrotoxicosis, including persistent abnormal fetal umbilical artery Doppler, fetal tachycardia and goitre observed during growth ultrasound scans. Initially, the patient was managed with antithyroid medications but required delivery at 34 weeks gestation due to deteriorating fetal health. This case illustrates that some pregnant women with previously treated Graves' disease may have persistently high levels of TSHRAb, which could cross the placenta to the fetus and result in fetal thyrotoxicosis requiring preterm delivery.