A longitudinal study of iodine excretion in normal pregnancy determined by inductively coupled plasma mass spectrometry

Abstract

We report here on a method for the determination of urine iodine by ICP-MS. The method proved to be fast, reliable and precise (within batch CVs <2.5%) and to have a low limit of detection (0.000 38 µmol L^–1). Iodine was determined in a total of 379 urine samples from 86 healthy pregnant women who gave samples at intervals of 4 weeks from 16 weeks pregnancy to 10 weeks post-partum. Fifty-five control urine samples were analysed from age-matched non-pregnant females. Iodine excretion (µmol of iodine per mol of creatinine) increased significantly from 28–40 weeks of pregnancy (p < 0.05), returning to non-pregnant control levels by 10 weeks post-partum. This study confirms the ability of our ICP-MS method to analyse large numbers of patient samples with the speed and performance acceptable for a routine assay.