URINARY IODINE CONCENTRATION: PREDICTOR OF BIRTH WEIGHT OR BIOMARKER FOR ASSESSING THE IODINE STATUS IN HEALTHY PREGNANT WOMEN, ONLY?

Abstract

Introduction: This study determined urine iodine concentration (UIC) during gestation, assessed the maternal iodine nutrition status and correlated it with gestational age at birth (GAB) and birth weight (BW).The measurement of UIC provides the best single measurement of the iodine nutritional status in population. Objective: Determination of UIC in pregnant women in North Macedonia. Methods: This prospective study assessed the iodine nutrition status during the course of pregnancy with reference of median UIC among 364 healthy pregnant women in different gestational age (in trimester and 5-week intervals). Results: The overall and the 1st to the 3rd trimester median UIC were: 183.7, 207, 189.75 and 169.28 [μg/L], respectively. The median UIC (μg/L) results according to 5-week interval in advancing gestation were: 232.34, 200.13, 152.81, 194.39, 181.28, 160.28, 169.41 and 175.24, respectively. We detected 5.22% (19/364) and 74.72% (272/364) with the median UIC < 50 μg/L and UIC ≥ 100 μg/L, respectively. In multiple regression, the median UIC (β = 0.0000767, P = 0.929) had no statistically significant prediction to the GAB. Disease prevalence results for mean UIC in detecting BW had no statistical significance: area under curve (AUC) = 0.521, z-statistic (0.340), sensitivity (45.83%), specificity (66.27%), predictive (6.59%) and P value (0.734). Conclusion: Iodine status of pregnant women in our study is generally sufficient by World Health Organization recommendations. The median UIC in each trimester and 5-week interval has statistically insignificant decrease in accordance to the advancing gestation. The median UIC has no significance in predicting GAB and BW.