Plasma mineral (selenium, zinc or copper) concentrations in the general pregnant population, adjusted for supplement intake, in relation to thyroid function

Abstract

The current study reports on first-trimester reference ranges of plasma mineral Se/Zn/Cu concentration in relation to free thyroxine (FT4), thyrotropin (TSH) and thyroid peroxidase antibodies (TPO-Ab), assessed at 12 weeks’ gestation in 2041 pregnant women, including 544 women not taking supplements containing Se/Zn/Cu. The reference range (2.5th – 97.5th percentiles) in these 544 women was 0.72 – 1.25 µmol/L for Se, 17.15 – 35.98 µmol/L for Cu, and 9.57 – 16.41 µmol/L for Zn. These women had significantly lower mean plasma Se concentration (0.94 µmol/L, SD 0.12) than those (N = 1479) taking Se/Zn/Cu supplements (1.03 µmol/L, SD, 0.14; P < 0.001) while the mean Cu (26.25 µmol/L) and Zn (12.55 µmol/L) concentrations were almost identical in these sub-groups. Women with hypothyroxinemia (FT4 below reference range with normal TSH) had significantly lower plasma Zn concentrations than euthyroid women. After adjusting for co-variates including supplement intake, plasma Se (negatively), Zn and Cu (positively) concentrations were significantly related to logFT4; Se and Cu (but not Zn) were positively and significantly related to logTSH. Women taking additional Se/Zn/Cu supplements were 1.46 (95% CI: 1.09 – 2.04) times less likely to have elevated titres of TPO-Ab at 12 weeks of gestation. We conclude that first-trimester Se reference ranges are influenced by Se-supplement intake while Cu and Zn ranges are not. Plasma mineral Se/Zn/Cu concentration are associated with thyroid FT4 and TSH concentrations. Se/Zn/Cu supplement intake affects TPO-Ab status. Future research should focus on the impact of trace-mineral status during gestation on thyroid function.

Prevalence of thyroid dysfunction in postpartum women with suboptimal iodine and selenium and adequate iron status

“…Similarly, one of the main findings in this cohort is that women with low plasma selenium concentration were more likely to have abnormal TSH concentrations (predominately < 0.4 mIU/L). A similar result was also reported in an observational study of pregnant Netherlands (n = 2041) at 12‐week gestation, 33 and the authors suggested human gonadotropin hormone may interfere with the role selenium plays in synthesising thyroid hormones. In contrast, a secondary analysis of the effects of antenatal selenium (60 µg/day) supplementation among UK pregnant women (n = 114) living in an area of mild‐to‐moderate iodine‐deficient area reported decreased TSH in the selenium supplementation group.…”

Evaluation of Serum Zinc Status of Pregnant Women in the China Adult Chronic Disease and Nutrition Surveillance (CACDNS) 2015

“…Besides, in sample selection, time of day, food and the consumed meals' interval, recent exercise, or other forms of stress all can result in obvious fluctuations [17]. In our study, serum zinc concentration was obviously higher than the value reported in previous Chinese studies [18], similar to the data in some countries and regional documents, but slightly lower than the results of USA [19], EU [20,21], Korea [22], and Japan [23]. In this regard, there was a trivial difference in zinc deficiency prevalence as compared to the significant changes in serum zinc concentration.…”

The Level of Zinc, Copper and Antioxidant Status in the Blood Serum of Women with Hashimoto’s Thyroiditis

“…The baseline characteristics of both groups are shown in Table 1. Hashimoto's disease was diagnosed based on value >35 U/L for anti-thyroid peroxidase (anti-TPO) antibodies and >20 U/L for thyroglobulin (anti-TG) antibodies [23,24]. In the group of women with Hashimoto's disease, 45.2% managed to balance the level of hormones regulating thyroid function.…”