Prediction of fetal Graves’ disease among pregnant women with Graves’ disease who have undergone thyroidectomy or radioactive iodine therapy: A retrospective observational study

Pregnant women with Graves' disease (GD) who have undergone thyroidectomy or radioactive iodine therapy can have high levels of thyroid-stimulating hormone (TSH) receptor antibodies, which are transferred to the fetus via the placenta, posing a risk for fetal GD. This retrospective observational study, conducted at two high-level perinatal medical centers in Tokyo and Osaka, Japan, aimed to identify predictors of fetal GD in pregnant women with GD who had undergone thyroidectomy or radioactive iodine therapy. In total, 65 women were included, and 79 singleton pregnancies and fetuses were analyzed. Fetal GD occurred in 17.7% of the 79 fetuses. Women in the fetal GD group had higher levels of TSH receptor antibodies and a higher prevalence of ophthalmopathies than did women in the non-fetal GD group. The receiver operating characteristic curve cutoff values of maternal TSH-binding inhibitory immunoglobulin (hereafter referred to as TRAb [TSH receptor antibody from a narrow perspective]) and thyroid-stimulating antibody (TSAb) levels predictive of fetal GD development were as follows: TRAb, 12.8 and 10.2 IU/L at 10 and 20 gestational weeks (GW), respectively; TSAb, 975.4% and 1,259.0% at 10 and 20 GW, respectively. Ophthalmopathy was a predictor of fetal GD; nonetheless, combining the ophthalmopathy and TRAb cutoff values did not improve predictive accuracy. A cutoff value of TRAb ≥10.2 IU/L at 20 GW (highest diagnostic accuracy found) could be a predictor of fetal GD risk for pregnant women with GD who undergo thyroidectomy or radioactive iodine therapy; thus, appropriate fetal monitoring should begin at around 20 GW.