Neonatal thyroid status in an area of iodine sufficiency

Background: Iodine deficiency constitutes a public health problem in many countries worldwide. Fetal neurodevelopment is affected by maternal iodine intake. The aim of present study was to assess urinary iodine excretion (UIE) in the 3 trimesters of pregnancy and evaluate its association with newborn thyroid function in Tehran, an area of iodine sufficiency. Methods: Based on median urinary iodine in 3 trimesters, 138 pregnant women were divided into 2 groups with UIE<150 (group I) and UlE150 mu g/l (group II). Cord blood samples of their newborns were evaluated for serum concentrations of TSH, T-3, T-4, free T-4 (FT4), and thyroglobolin. Quartiles of UIE were also determined. Correlations between mothers' UIE and newborns' thyroid function in both groups were investigated. Results: Fifty-two pregnant women (38%) had median UIE<150 mu g/l and 86 had (62%) UIE >= 150 mu g/l. Median UIE in groups land II in the 1(st), 2(nd), and 3(rd) trimesters were 125 and 212 mu g/l 97 and 213 mu g/l, 93 and 227 mu g/l, respectively. No significant difference was seen in thyroid function of newborns in the 2 groups. Mean concentrations of T-4, T-3, FT4, and TSH of newborn did not show significant difference in median UIE of mothers in various quartiles. Conclusion: This study shows that newborns, irrespective of mothers' UIE, in an area with a sustained iodine supplementation program, may not be at risk of alterations in thyroid functions. (J. Endocrinol. Invest. 34: 197-200, 2011) (C) 2011, Editrice Kurtis