Yindi Liu1, Arash Derakhshan2, Robin Baan3, Johannes Krabbe3, Tim Korevaar4
(1) Department of Internal Medicine, Erasmus University Medical Center, Rotterdam , Netherlands. (2) Department of Internal Medicine, Erasmus University Medical Center, Rotterdam , Netherlands. (3) Department of Clinical Chemistry and Laboratory Medicine, Medisch Spectrum Twente, Enschede, Netherlands. (4) Department of Internal Medicine, Erasmus University Medical Center, Rotterdam , Netherlands.
Background:
Iodine is necessary for the synthesis of thyroid hormones. As the well-known inhibitors of sodium/iodide symporter (NIS), perchlorate, thiocyanate, and nitrate can competitively inhibit the thyroidal uptake of iodine. Therefore, exposure to these NIS inhibitors during pregnancy may lower gestational thyroid hormone availability.
Objectives:
We aimed to investigate the association of maternal exposure to NIS inhibitors with gestational thyroid function.
Methods:
We utilized data from Generation R, a population-based prospective birth cohort (Rotterdam, the Netherlands). We included 1,221 pregnant women with available data on urinary perchlorate, thiocyanate, and nitrate, and maternal serum thyroid stimulating hormone (TSH) and free thyroxine (FT4) in early pregnancy. We studied the association of urinary perchlorate, thiocyanate, and nitrate with maternal thyroid function tests using multivariable linear regression models and weighted quantile sum (WQS) regression models.
Results:
Maternal exposure to perchlorate was not associated with maternal thyroid function tests. Higher exposure to thiocyanate was associated with higher TSH concentrations (beta: 0.03, 95% confidence interval [CI]: 0.01, 0.06) and lower FT4 concentrations (beta: -0.16, 95% CI: -0.31, -0.003). Higher exposure to nitrate was associated with higher TSH concentrations (beta: 0.04, 95% CI: 0.002, 0.08). We identified that the mixture of perchlorate, thiocyanate, and nitrate was negatively associated with FT4 concentrations (beta: -0.26, 95% CI: -0.46, -0.07).
Conclusion:
Higher maternal exposure to NIS inhibitors may interfere with the thyroid system during pregnancy.