Effect of low-dose selenium on thyroid autoimmunity and thyroid function in UK pregnant women with mild-to-moderate iodine deficiency

Abstract

PurposeSelenium is an essential trace mineral and a component of selenoproteins that are involved in the production of thyroid hormones and in regulating the immune response. We aimed to explore the effect of low-dose selenium supplementation on thyroid peroxidase antibody (TPO-Ab) concentration and thyroid function in pregnant women from a mild-to-moderate iodine-deficient population.MethodsSamples and data were from a secondary analysis of Selenium in PRegnancy INTervention (SPRINT), a double-blind, randomized, placebo-controlled study that recruited 230 women with singleton pregnancies from a UK antenatal clinic at 12 weeks of gestation. Women were randomized to receive 60 µg/day selenium or placebo until delivery. Serum thyroid peroxidase antibodies (TPO-Ab), thyrotropin (TSH) and free thyroxine (FT4) were measured at 12, 20 and 35 weeks and thyroglobulin antibodies (Tg-Ab) at 12 weeks.Results93.5 % of participants completed the study. Se supplementation had no more effect than placebo in decreasing TPO-Ab concentration or the prevalence of TPO-Ab positivity during the course of pregnancy. In women who were either TPO-Ab or Tg-Ab negative at baseline (Thy-Ab−ve), TSH increased and FT4 decreased significantly throughout gestation (P < 0.001), with no difference between treatment groups. In women who were Thy-Ab+ve at baseline, TSH tended to decrease and was lower than placebo at 35 weeks (P = 0.050). FT4 fell more on Se than placebo supplementation and was significantly lower at 35 weeks (P = 0.029).ConclusionsLow-dose selenium supplementation in pregnant women with mild-to-moderate deficiency had no effect on TPO-Ab concentration, but tended to change thyroid function in Thy-Ab+ve women.

Does selenium supplementation affect thyroid function? Results from a randomized, controlled, double-blinded trial in a Danish population

“…Effects were significant in our study already after 6 months intervention. Interestingly, our short-term findings are in accordance with a recent study, in which w6 months low-dose selenium supplementation decreased FT 4 and tended to decrease TSH, when compared with placebo (21). The comparability is however limited as study subjects were pregnant women and effects were seen only in thyroid antibody-positive individuals.…”

“…For this, we applied a population averaged procedure assuming a linear relationship between outcome and covariates, by use of population-averaged generalized estimating equations (PA-GEE) combined with a sandwich estimator (21). This approach accommodates repeated measurements without requiring a constant within-subject variation, and encompasses continuous non-normal outcomes.…”

The role of selenium in thyroid gland pathophysiology

“…The presented results suggest beneficial effects of selenium on the autoimmune diseases of the TG [83,120]. In women at risk of postpartum thyroiditis, proper supplementation of the microelement may provide a prophylactic effect against the disease, although the data from clinical studies still require additional confirmation [121,122].…”

“…Opisane powyżej wyniki sugerują korzystny wpływ selenu na przebieg i występowanie autoimmunologicznych chorób tarczycy [83,120]. U kobiet zagrożonych wystąpieniem poporodowego zapalenia tarczycy właściwa podaż wspomnianego mikroelementu może zapobiegać tej jednostce chorobowej, choć dane płynące z badań klinicznych wymagają jeszcze dodatkowego potwierdzenia [121,122].…”

A 2016 Italian Survey about the Clinical Use of Selenium in Thyroid Disease

“…However, one study showed significantly reduced postpartum thyroid dysfunction with the administration of Se 200 μg/day from midpregnancy onwards [10] . A double-blind, randomized, placebo-controlled study demonstrated that supplementation with Se 60 μg/ day in pregnant women with mild-to-moderate Se deficiency did not impact TPOAb concentration, but it did tend to alter thyroid function in TPOAb-positive women [19] .…”