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J Clin Endocrinol Metab. 2010 Jul;95(7):3207-15. doi: 10.1210/jc.2010-0014. Epub 2010 Apr 28.

Perchlorate and thiocyanate exposure and thyroid function in first-trimester pregnant women.

Author information

1
Section of Endocrinology, Diabetes, and Nutrition, Boston University Medical Center, 88 East Newton Street, Evans 201, Boston, MA 02118, USA. Elizabeth.pearce@bmc.org

Abstract

CONTEXT:

Thyroid hormone, requiring adequate maternal iodine intake, is critical for fetal neurodevelopment. Perchlorate decreases thyroidal iodine uptake by competitively inhibiting the sodium/iodide symporter. It is unclear whether environmental perchlorate exposure adversely affects thyroid function in pregnant women. Thiocyanate, derived from foods and cigarette smoke, is a less potent competitive sodium/iodide symporter inhibitor than perchlorate.

OBJECTIVE:

Our objective was to determine whether environmental perchlorate and/or thiocyanate exposure is associated with alterations in thyroid function in pregnancy.

DESIGN AND SETTING:

We conducted a cross-sectional study at health centers in Cardiff, Wales, and Turin, Italy.

PATIENTS:

During 2002-2006, 22,000 women at less than 16 wk gestation were enrolled in the Controlled Antenatal Thyroid Screening Study. Subsets of 261 hypothyroid/hypothyroxinemic and 526 euthyroid women from Turin and 374 hypothyroid/hypothyroxinemic and 480 euthyroid women from Cardiff were selected based on availability of stored urine samples and thyroid function data.

MAIN OUTCOME MEASURES:

Urinary iodine, thiocyanate, and perchlorate and serum TSH, free T(4) (FT(4)), and thyroperoxidase antibody were measured.

RESULTS:

Urinary iodine was low: median 98 microg/liter in Cardiff and 52 microg/liter in Turin. Urine perchlorate was detectable in all women. The median (range) urinary perchlorate concentration was 5 microg/liter (0.04-168 microg/liter) in Turin and 2 microg/liter (0.02-368 microg/liter) in Cardiff. There were no associations between urine perchlorate concentrations and serum TSH or FT(4) in the individual euthyroid or hypothyroid/hypothyroxinemic cohorts. In multivariable linear analyses, log perchlorate was not a predictor of serum FT(4) or TSH.

CONCLUSIONS:

Low-level perchlorate exposure is ubiquitous but did not affect thyroid function in this cohort of iodine-deficient pregnant women.

PMID:
20427488
DOI:
10.1210/jc.2010-0014
[Indexed for MEDLINE]

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