Assessing the relationship between perfluoroalkyl substances, thyroid hormones and binding proteins in pregnant women; a longitudinal mixed effects approach. (April 2015)

• Record Type: Journal Article
• Authors: Berg, Vivian; Nøst, Therese Haugdahl; Hansen, Solrunn; Elverland, Astrid; Veyhe, Anna-Sofía; Jorde, Rolf; Odland, Jon Øyvind; Sandanger, Torkjel Manning
• Is Part Of: Environment international. Volume 77(2015:Apr.)
• Page Start: 63
• Page End: 69
• Publication Date: 2015-04
• Subjects: Anti-TPOs anti-thyroid peroxidase antibodies -- HTP hypothalamic pituitary -- LOD limit of detection -- MISA The Northern Norway Mother-and-Child contaminant Cohort Study -- PFASs poly- and perfluoroalkyl substances -- PFDA perfluorodecanoate -- PFDoDA perfluorododecanoate -- PFHpS perfluoroheptane sulfonate -- PFHxS perfluorohexane sulfonate -- PFNA perfluorononanoate -- PFOA perfluorooctanoate -- PFOS perfluorooctane sulfonate -- PFUnDA perfluoroundecanoate -- PLS partial least square -- T3 triiodothyronine -- FT3 free triiodothyronine -- T4 thyroxin -- FT4 free thyroxin -- T-uptake thyroxin binding capacity -- TBG thyroid binding globulin -- TH thyroid hormone -- TH-BP thyroid hormone binding protein -- TSH thyroid stimulating hormone -- TTR transthyretin -- UHPLC–MS/MS ultrahigh pressure liquid chromatography triple–quadrupole mass-spectrometry; Thyroid hormones -- Perfluoroalkyl substances -- Pregnant women -- Thyroxin binding capacity -- Endocrine disruption; Environmental protection -- Periodicals; Environmental health -- Periodicals; Environmental monitoring -- Periodicals; Environmental Monitoring -- Periodicals; Environnement -- Protection -- Périodiques; Hygiène du milieu -- Périodiques; Environnement -- Surveillance -- Périodiques; Environmental health; Environmental monitoring; Environmental protection; Periodicals; 333.705
• DOI: 10.1016/j.envint.2015.01.007
• Languages: English
• ISSNs: 0160-4120

Abstract

Abstract: The mechanisms involved in thyroid homeostasis are complex, and perfluoroalkyl substances (PFASs) have been indicated to interfere at several levels in this endocrine system. Disruption of the maternal thyroid homeostasis during early pregnancy is of particular concern, where subclinical changes in maternal thyroid hormones (THs) may affect embryonic and foetal development. The present study investigated associations between THs, thyroid binding proteins (TH-BPs) and PFAS concentrations in pregnant women from Northern Norway. Women participating in The Northern Norway Mother-and-Child contaminant Cohort Study (MISA) donated a blood sample at three visits related to their pregnancy and postpartum period (during the second trimester, 3 days and 6 weeks after delivery) in the period 2007–2009. Participants were assigned to quartiles according to PFAS concentrations during the second trimester and mixed effects linear models were used to investigate potential associations between PFASs and repeated measurements of THs, TH-BPs, thyroxin binding capacity and thyroid peroxidase antibodies (anti-TPOs). Women within the highest perfluorooctane sulfonate (PFOS) quartile had 24% higher mean concentrations of thyroid stimulating hormone (TSH) compared to the first quartile at all sampling points. Women within the highest quartiles of perfluorodecanoate (PFDA) had 4% lower mean concentrations of triiodothyronine (T3) and women within the highest quartile of perfluoroundecanoate (PFUnDA) had 3% lower mean concentrations of free triiodothyronine (FT3). Further, the difference in concentrations and the changes between three time points were the same for the PFAS quartiles. Thyroxin binding capacity was associated with all the THs and TH-BPs, and was selected as a holistic adjustment for individual changes in TH homeostasis during pregnancy. Finally, adjusting for maternal iodine status did not influence the model predictions. Findings in the present study suggest modifications of TH homeostasis by PFASs in a background exposed maternal population. The variation in levels of THs between PFAS quartiles was within normal reference ranges and may not be of clinical significance in the pregnant woman. However, subtle individual changes in maternal THs may have significant consequences for foetal health. Highlights: Pregnancy is a susceptibility period for subclinical changes in maternal THs. PFASs influence the TH homeostasis in this background exposed maternal population. Thyroxin binding capacity was the most important covariate in predicting TH levels. PFOS was positively associated with TSH. PFDA and PFUnDA were inversely associated with T3 and FT3, respectively.