Thyroid Peroxidase Antibodies as a Marker of Iodine Status in Healthy Euthyroid Women in First Trimester of Pregnancy Visiting a Tertiary Care Hospital in Raipur, India

Abstract

BACKGROUND The importance of adequate iodine status in pregnancy is undoubted as its deficiency is associated with adverse pregnancy outcomes for the mother as well as the foetus and neonate. Although median urine iodine concentration can assess iodine status of the population but not at an individual level. The purpose of this study was to assess the nutritional status of iodine and identify its effects on thyroid function during the first trimester of pregnancy. METHODS The study was carried out on 341 euthyroid healthy pregnant women using urine iodine concentration and other parameters of thyroid panel at a tertiary care hospital. RESULTS Median (interquartile range) urine iodine concentration and thyroid stimulating hormone (TSH) were 227.37 (161.7, 343.86) μg / L and 1.8 (1.1, 2.7) mIU / L respectively and Mean ± SD of free thyroxine and thyroid peroxidase antibodies were 14.53 ± 2.02 pmol / L and 38.23 ± 9.29 kIU / L respectively. Only thyroid peroxidase antibodies showed significant difference across groups with different iodine status. A positive correlation of urine iodine concentration (UIC) with thyroid peroxidase antibodies was observed (r = 0.137, P = 0.011). Multiple regression analysis revealed that thyroid peroxidase antibodies can serve as an independent predictor of iodine status in the presence of normal levels of TSH and FT4 (t - 3.063, CI; 0.880, 4.038, P = 0.002). CONCLUSIONS Thyroid peroxidase antibodies progressed positively with increase in urine iodine concentration indicating its role as a marker of iodine nutritional status and for early identification of women who can develop autoimmune thyroiditis resulting in hypothyroidism even prior to elevation of thyroid stimulating hormone levels. KEY WORDS Anti-TPO Ab, Free Thyroxine, Thyroid Stimulating Hormone, Urine Iodine Concentration