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.
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.
Authors: Laura N Vandenberg; Theo Colborn; Tyrone B Hayes; Jerrold J Heindel; David R Jacobs; Duk-Hee Lee; Toshi Shioda; Ana M Soto; Frederick S vom Saal; Wade V Welshons; R Thomas Zoeller; John Peterson Myers Journal: Endocr Rev Date: 2012-03-14 Impact factor: 19.871
Authors: Angela M Leung; Pamela M Katz; Xuemei He; Denice S Feig; Elizabeth N Pearce; Lewis E Braverman Journal: Thyroid Date: 2013-09-11 Impact factor: 6.568
Authors: Angela M Leung; Andrew Lamar; Xuemei He; Lewis E Braverman; Elizabeth N Pearce Journal: J Clin Endocrinol Metab Date: 2011-05-25 Impact factor: 5.958
Authors: Mary E Mortensen; Rebecca Birch; Lee-Yang Wong; Liza Valentin-Blasini; Elizabeth B Boyle; Kathleen L Caldwell; Lori S Merrill; John Moye; Benjamin C Blount Journal: Environ Res Date: 2016-05-19 Impact factor: 6.498