Assessment of iodine intake in mildly iodine-deficient pregnant women by a new automated kinetic urinary iodine determination method

Abstract

Maternal iodine deficiency can compromise the thyroid status of the mother, fetus and newborn child. Therefore, it is important to assess the iodine excretion level of groups of pregnant women. In this study we aimed to determine iodine intake in pregnancy using a recently reported automated kinetic method for urinary iodine determination. Urinary iodine measurements of 123 pregnant women (18 first, 28 second and 77 third trimester) were carried out using a new automated kinetic assay based on the Sandell-Kolthoff reaction at 37 degrees C and its kinetic measurement at 340 nm in a random-access automated analyzer after ammonium persulfate digestion at 95 degrees C in a water bath with +/-0.1 degree C precision. Statistical analyses were carried out using SPSS software. Whole group, first trimester, second trimester and third trimester urinary iodine concentrations (mean+/-SD) in pregnant women were 1.13+/-0.81, 1.08+/-0.71, 0.86+/-0.58 and 1.27+/-0.87 micromol/L, respectively. The urinary iodine concentration significantly increased with gestational age (p<0.05). We found that our study group was mildly iodine-deficient according to WHO criteria. Furthermore, the pregnant women were found to be mildly iodine-deficient in the first and third trimesters and moderately so in the second trimester. The only statistical difference was between second and third trimester values (p<0.05). Even though the increased iodine deficiency in the second trimester is not useful for early detection of iodine deficiency in pregnancy, the severity of this deficiency in the second trimester may lead to important effects on thyroid metabolism for both mother and fetus. Our study suggests that the iodine excretion of pregnant women living in iodine-deficient areas could be assessed using this fast and automated method.