IODINE SUPPLEMENTATION AND THYROID STATUS IN HEALTHY PREGNANT WOMEN IN IODINE-REPLETE REGION

Abstract

Background: Optimal iodine intake is essential for proper function of the thyroid in pregnancy, affecting thus the foetal development. Recent data worldwide have revealed insufficient iodine intake in pregnant women in certain countries with confirmed iodine sufficiency and raise the issue of iodine supplementation in this population. The objective of the study was to determine the effects of the iodine supplementation in pregnant women (PW) on their thyroid status and compare the findings with the data of pregnant women without iodine supplementation, all living under iodine sufficiency of general population. Material and Methods: The case control study was performed on total 543 PW (aged 15 – 40 years), 267 of which were taking iodine supplements. Iodine status was assessed as median urinary concentration and thyroid function tests (TFTs) were performed by chemiluminescent immunoassays. Data analysis was performed by descriptive and nonparametric statistics. Results: The overall median urinary iodine concentration (UIC) in PW was 167,5 μg/L. The median value of the group with iodine supplementation was higher compared to non-supplementation group (180,5 μg/L vs 160,2 μg/L), but the difference was not statistically significant. The median value was higher for thyroid stimulating hormone (TSH) in the group of PW with iodine supplementation (1,8 mIU/L vs. 1,6 mIU/L), while for thyroglobulin (Tg) in the group without iodine supplementation (11,4 μg/L vs. 10,5 μg/L). The difference in free thyroxine (FT4) results between the two groups was not statistically significant. Conclusions: Living in a long-term iodine sufficient region, PW on iodine supplementation with 150 μg/day remained euthyroid, without evidence of increased incidence of iodine-induced thyroid disorders.