Section of Endocrinology, Diabetes and Nutrition, Boston University School of Medicine, Boston, MA.
Objective: Thyroid hormone, requiring adequate maternal iodine intake, is critical for neurodevelopment in utero. Perchlorate decreases uptake of iodine into the thyroid gland by competitively inhibiting the sodium/iodide symporter (NIS). It is unclear whether environmental perchlorate exposure adversely affects thyroid function in first trimester pregnant women.Methods: Urinary iodine and perchlorate measurements and thyroid function tests were obtained in 134 pregnant women from Los Angeles, CA (mean ± SD 9.1 ± 2.2 weeks gestation) and 107 pregnant women from Córdoba, Argentina (mean 10.0 ± 2.0 weeks).Results: Median urinary iodine values were 144 μg/L in California and 130 μg/L in Argentina. Urinary perchlorate levels were detectable in all women: median (range) in California 7.8 (0.4 – 284) μg/L; and in Argentina 13.5 (1.1 – 676) μg/L. Serum thyroperoxidase antibodies (TPO Ab) were detectable in 16% of women from California and 17% of women from Argentina. Using Spearman rank correlation analyses, there was no association between urinary perchlorate concentrations and serum TSH, free T4 index, or total T3 values, including within the subset of women with urinary iodine values less than 100 μg/L. In multivariate analyses using the combined Argentina and California data sets adjusting for urinary iodine concentrations, urine creatinine, gestational age, and TPO Ab status, urine perchlorate was not a significant predictor of thyroid function.Conclusions: Low-level perchlorate exposure is ubiquitous, but is not associated with alteration in thyroid function tests among women in the first trimester of pregnancy.
Abstract Source: National Library of Medicine
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