Thyroid hormones in relation to toxic metal exposure in pregnancy, and potential interactions with iodine and selenium.
Essential elements
Pregnancy
Thyroid stimulating hormone
Thyroxine
Toxic metals
Triiodothyronine
Journal
Environment international
ISSN: 1873-6750
Titre abrégé: Environ Int
Pays: Netherlands
ID NLM: 7807270
Informations de publication
Date de publication:
12 2021
12 2021
Historique:
received:
05
03
2021
revised:
03
09
2021
accepted:
05
09
2021
pubmed:
17
9
2021
medline:
21
10
2021
entrez:
16
9
2021
Statut:
ppublish
Résumé
Several endocrine-disrupting metals may affect thyroid function, but the few available studies of exposure during pregnancy and thyroid hormones are inconclusive. To explore if environmental exposure to cadmium (Cd), lead (Pb), and methylmercury (MeHg) impacts thyroid function in pregnancy, and interacts with iodine and selenium status. Women in a Swedish birth cohort provided blood and urine samples in early third trimester. Concentrations of erythrocyte Cd, Pb, and Hg (n = 544), urinary Cd and iodine (n = 542) and plasma selenium (n = 548) were measured using inductively coupled plasma-mass spectrometry.Free and total thyroxine (fT4, tT4) and triiodothyronine (fT3, tT3), and thyroid stimulating hormone (TSH), were measured in plasma (n = 548) with electrochemiluminescence immunoassays. Metal-hormone associations were assessed in regression models, and metal mixture effects and metal-nutrient interactions were explored in Bayesian kernel machine regression (BKMR). In multivariable-adjusted regression models, a doubling of urinary Cd was associated with a mean increase in tT4 of 2.7 nmol/L (95% CI: 0.78, 4.6), and in fT3 and tT3 of 0.06 pmol/L (0.02, 0.10) and 0.09 nmol/L (0.05, 0.13), respectively. A doubling of urinary Cd was associated with a -0.002 (-0.003, -0.001) and -0.03 (-0.05, -0.02) decrease in the fT4:tT4 and fT3:tT3 ratio, respectively. A doubling of erythrocyte Hg (>1 µg/kg) was associated with a decrease in fT3 and tT3 by -0.11 pmol/L (-0.16, -0.05) and -0.11 nmol/L (-0.16, -0.06), respectively, and a -0.013 (-0.02, -0.01) decrease in the fT3:fT4 ratio. BKMR did not indicate any mixture effect of toxic metals or interactions between metals and iodine or selenium in relation to the hormones. Our findings suggest that exposure to Cd and Hg, at levels globally prevalent through the diet, may affect thyroid function during pregnancy, independently of iodine and selenium levels. Further studies on potential implications for maternal and child health are warranted.
Sections du résumé
BACKGROUND
Several endocrine-disrupting metals may affect thyroid function, but the few available studies of exposure during pregnancy and thyroid hormones are inconclusive.
OBJECTIVE
To explore if environmental exposure to cadmium (Cd), lead (Pb), and methylmercury (MeHg) impacts thyroid function in pregnancy, and interacts with iodine and selenium status.
METHODS
Women in a Swedish birth cohort provided blood and urine samples in early third trimester. Concentrations of erythrocyte Cd, Pb, and Hg (n = 544), urinary Cd and iodine (n = 542) and plasma selenium (n = 548) were measured using inductively coupled plasma-mass spectrometry.Free and total thyroxine (fT4, tT4) and triiodothyronine (fT3, tT3), and thyroid stimulating hormone (TSH), were measured in plasma (n = 548) with electrochemiluminescence immunoassays. Metal-hormone associations were assessed in regression models, and metal mixture effects and metal-nutrient interactions were explored in Bayesian kernel machine regression (BKMR).
RESULTS
In multivariable-adjusted regression models, a doubling of urinary Cd was associated with a mean increase in tT4 of 2.7 nmol/L (95% CI: 0.78, 4.6), and in fT3 and tT3 of 0.06 pmol/L (0.02, 0.10) and 0.09 nmol/L (0.05, 0.13), respectively. A doubling of urinary Cd was associated with a -0.002 (-0.003, -0.001) and -0.03 (-0.05, -0.02) decrease in the fT4:tT4 and fT3:tT3 ratio, respectively. A doubling of erythrocyte Hg (>1 µg/kg) was associated with a decrease in fT3 and tT3 by -0.11 pmol/L (-0.16, -0.05) and -0.11 nmol/L (-0.16, -0.06), respectively, and a -0.013 (-0.02, -0.01) decrease in the fT3:fT4 ratio. BKMR did not indicate any mixture effect of toxic metals or interactions between metals and iodine or selenium in relation to the hormones.
CONCLUSION
Our findings suggest that exposure to Cd and Hg, at levels globally prevalent through the diet, may affect thyroid function during pregnancy, independently of iodine and selenium levels. Further studies on potential implications for maternal and child health are warranted.
Identifiants
pubmed: 34530290
pii: S0160-4120(21)00494-3
doi: 10.1016/j.envint.2021.106869
pii:
doi:
Substances chimiques
Thyroid Hormones
0
Triiodothyronine
06LU7C9H1V
Thyrotropin
9002-71-5
Iodine
9679TC07X4
Selenium
H6241UJ22B
Thyroxine
Q51BO43MG4
Types de publication
Journal Article
Research Support, Non-U.S. Gov't
Langues
eng
Sous-ensembles de citation
IM
Pagination
106869Informations de copyright
Copyright © 2021 The Author(s). Published by Elsevier Ltd.. All rights reserved.