Severe selenium deficits in pregnant women irrespective of autoimmune thyroid disease in an area with marginal...

Selenium (Se) deficiency is related to an increased risk of preterm labor, miscarriage, preeclampsia, gestational diabetes, and other obstetric complications. As the Se status declines during pregnancy, we hypothesized that the decline may be exacerbated in women with autoimmune thyroid disease (AITD).

Pregnant women (n=74; 30 [23-38] years) were consecutively recruited from the district of Warsaw, Poland, and divided into healthy subjects (HS, n=45), and women with a diagnosis of AITD (AITD, n=29). Thyroglobulin antibodies (TG-aAb), thyroid peroxidase antibodies (TPO-aAb), TSH, free T3, free T4, total T3, and total T4, as well as urine iodine excretion were determined. Se status was assessed by serum Se and selenoprotein P (SELENOP) concentrations. Thyroid volume was evaluated by ultrasonography.

Serum Se and SELENOP concentrations were relatively low in both control and AITD women. A Se deficit according to WHO definition (<45μg/l) was observed in 0%, 3.4%, 28.6% and 4.5%, 18.2%, 35.5% of women in the AITD and HS group, respectively, during the 1st, 2nd, and 3rd trimester. From first to third trimester, TPO-aAb and TG-aAb declined in AITD by 71% and 60%, respectively. The decline in TPO- and TG-aAb was unrelated to the Se status.

In this area of habitual low Se intake, a high proportion of women developed a severe Se deficit during pregnancy, irrespective of AITD status. This decline must be considered as a preventable risk factor for pregnancy complications of relevance to both the unborn child and the pregnant mother.