Endocrine Abstracts

Background: Selenium (Se) sufficiency is beneficial for thyroid metabolism and pregnancy course due to its antioxidant and anti-inflammatory properties. As a part of selenoenzymes, it ameliorates autoimmune thyroid disease (AITD) progression in mothers and provides proper neurogenesis in fetuses. Despite lacking or conflicting recommendations for its supplementation in pregnancy, Se is used in a clinical setting, as a common constituent of multivitamin pregnancy diet supplements.

Objectives: The aim of the study was to evaluate Se supply and real-life supplementation effectiveness in pregnancy, based on Se biomarkers assessment in mothers and their newborns.

Methods: 115 mother-child pairs were recruited at term delivery from obstetric department in one Polish centre. By the medical interview Se supplementation during pregnancy was assessed. The blood was collected before childbirth in mothers and during the third phase of delivery from the newborns’ cord blood. Se status was assessed by measuring serum Se with Total Reflection X-ray Fluorescence analysis (on TXRF spectrometer S4 T-STAR) and selenoprotein P (SELENOP) with colorimetric enzyme immunoassay (selenOtest) concentrations and glutathione peroxidase 3 (GPX3) activity with a coupled enzymatic assay with t-butyl hydroperoxide as a substrate. This research was funded by National Science Centre in Poland (2019/33/N/NZ5/02303) as PRELUDIUM-17 grant.

Results: Se intake was declared by 30% of women, using multi-micronutrient supplements, with a mean Se dosage (± SD) of 42 ± 14 µg/day. The whole group was deficient in Se in 89% (Se <70 µg/l) and SELENOP in 77%. Median serum Se (54 vs. 58 µg/l), SELENOP (2.2 vs. 2.3 mg/l), or GPX3 (199 vs. 208.5 U/l) concentrations were slightly but not significantly higher in the supplemented than non-supplemented group. However, in the subgroups of low (<55 µg/day) and moderate (≥ 55 µg/day) daily Se dosage, median SELENOP was significantly higher in the latter group (1.84 vs. 3.17 mg/l, P=0.006). Additionally, positive correlations of Se (r=0.4, P<0.001) within mother-newborn pairs and SELENOP (r=0.78, P<0.001; r=0.72, P<0.001), GPX3 (r=0.78, P<0.001; r=0.53, P<0.001) with Se between mothers and newborns adequately was observed.

Conclusions: Se supplementation from pregnancy multivitamin formulas was ineffective in the presented cohort. The mothers’ Se supply reflects Se bioavailability for newborns. Considering diversity in geographical Se stores, differences in diet and individual Se level, no common guidelines can be applied worldwide, thus, there is a need of local Se status verification and adjusted recommendations.