Partial prediction of postpartum Graves' thyrotoxicosis by sensitive bioassay for thyroid-stimulating antibody measured in early pregnancy.

Graves' disease often occurs after delivery. However, it has been difficult to predict who will develop Graves' hyperthyroidism. We attempted to predict postpartum onset of Graves' disease by measuring anti-TSH receptor antibodies (TRAb) and thyroid-stimulating antibodies (TSAb) in early pregnancy. TRAb was measured by a third generation assay and TSAb was measured by a newly developed sensitive bioassay. In 690 early pregnant women, 2 showed borderline TRAb positive reactions. However, none of them developed Graves' disease after delivery. Thirty-eight of 690 pregnant women were positive for anti-thyroid peroxidase antibodies (TPOAb) and 4 were positive for TSAb. Two of these 4 women developed postpartum Graves' hyperthyroidism. These findings indicate that the third generation TRAb assay was not useful, but that the sensitive TSAb bioassay was moderately useful for predicting the postpartum onset of Graves' hyperthyroidism.

Thyroid function in early pregnancy in Japanese healthy women: relation to urinary iodine excretion, emesis, and fetal and child development.

CONTEXT: The effect of constant rich iodine intake, especially during pregnancy, has not been well understood. OBJECTIVE: The objective was to examine urinary iodine excretion and thyroid function in early pregnancy in Japanese healthy women. We also studied fetal maturation and child development in these women. DESIGN AND SETTING: This study was an observational, prospective study conducted at a maternity hospital. SUBJECTS: Subjects were 622 pregnant women who visited a maternity hospital consecutively in early gestation. Subjects with positive thyroid antibodies were excluded, and finally 514 subjects were examined. Offspring subjects were infants born to the maternal subjects. MAIN OUTCOME MEASURES: Thyroid function, serum thyroperoxidase antibodies, and urinary concentrations of iodine were measured at the initial obstetrical visit. The fetal maturation scores estimated by the Dubowitz and Ballard methods in newly born infants were assessed. A child developmental test was performed using the Enjoji Scale up to 12 months of age. RESULTS: The distribution of urinary iodine concentrations was large, and the average was extremely high. There were significant positive correlations between urinary iodine and serum TSH (r = 0.1326; P < 0.005). Serum TSH during early pregnancy in mothers had no relevance to parameters in neonates, scores of fetal maturation, or child developmental testing in their infants. CONCLUSIONS: Iodine excess during early pregnancy seems to have no adverse effects on the fetus in healthy Japanese women. To avoid hypothyroidism, reducing excess dietary iodine intake to moderate intake may be beneficial for pregnant woman in Japan.