Association between mercury exposure and thyroid hormones levels: A meta-analysis

Qi Hu; Xiumei Han; Guangzhu Dong; Wu Yan; Xu Wang; Francis Manyori Bigambo; Kacey Fang; Yankai Xia; Ting Chen; Xinru Wang

doi:10.1016/j.envres.2021.110928

Association between mercury exposure and thyroid hormones levels: A meta-analysis

Environ Res. 2021 May:196:110928. doi: 10.1016/j.envres.2021.110928. Epub 2021 Feb 26.

Authors

Qi Hu¹, Xiumei Han¹, Guangzhu Dong¹, Wu Yan¹, Xu Wang², Francis Manyori Bigambo¹, Kacey Fang³, Yankai Xia¹, Ting Chen⁴, Xinru Wang⁵

Affiliations

¹ State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China.
² Children's hospital of Nanjing medical university, Nanjing, China.
³ Department of Cognitive Science, Yale University, New Haven, CT, USA.
⁴ Nanjing Maternity and Child Health Care Hospital, Women's Hospital of Nanjing Medical University, Nanjing, 210004, China. Electronic address: chenting@njmu.edu.cn.
⁵ State Key Laboratory of Reproductive Medicine, Center for Global Health, School of Public Health, Nanjing Medical University, Nanjing, 211166, China; Key Laboratory of Modern Toxicology of Ministry of Education, School of Public Health, Nanjing Medical University, Nanjing, 211166, China. Electronic address: xrwang@njmu.edu.cn.

PMID: 33640496
DOI: 10.1016/j.envres.2021.110928

Abstract

Background: The relationship between mercury (Hg) exposure and thyroid hormones (THs) levels in the general population has been inconclusive. We conducted a random effects model meta-analysis to identify the association between Hg exposure and THs levels in the general population.

Methods: This meta-analysis were performed based on the PECO questions (P = general population; E =1ug/L Hg in blood and urine; C =1ug/L incremental increase on; and O = variation of THs levels). We searched four electronic databases including PubMed, Web of Science, Embase, and Cochrane Library for studies published on or before 20th July 2020. Prospective and cross-sectional studies that evaluated the association between Hg exposure and the levels of thyroid stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), free triiodothyronine (FT3), and free thyroxine (FT4) were included. We also assessed aggregate risks for the reliability of the included studies.

Results: Initially, we retrieved 4889 articles. 18 studies met our inclusion criteria after screening and 13 articles were eligible to be included in the meta-analysis. The meta-analysis results suggest that blood Hg may be significantly associated with THs levels. The presence of Hg in blood may significantly increase the levels of TSH (β=0.55; 95%CI: 0.20,0.90; p < 0.001) and FT4 (β=0.47; 95%CI: 0.11,0.82; p < 0.001), with the opposite association in T4 (β=-0.02; 95%CI: 0.02, -0.01; p < 0.001). For the subgroup analysis, blood Hg was positively correlated with TSH levels in children and adolescents (β=0.62; 95%CI: 0.09, 1.15; p < 0.001) and FT4 levels in pregnant women (β=1.00; 95%CI: 0.99, 1.00; p < 0.001) respectively.

Conclusions: This meta-analysis indicates that exposure to Hg in blood could significantly corrrelate with the levels of TSH, T4, and FT4 in the general population. Therefore, it is crucial to control the use of Hg and strengthen protection of the thyroid.

Keywords: Heavy metal; Mercury exposure; Meta-analysis; Thyroid function; Thyroid hormone.

Publication types

Meta-Analysis
Research Support, Non-U.S. Gov't

MeSH terms

Adolescent
Child
Cross-Sectional Studies
Female
Humans
Mercury* / toxicity
Pregnancy
Prospective Studies
Reproducibility of Results
Thyroid Gland*
Thyroid Hormones
Thyrotropin
Thyroxine
Triiodothyronine

Substances

Thyroid Hormones
Triiodothyronine
Thyrotropin
Mercury
Thyroxine