Analysis of Urine Iodine Concentration by Inductively Coupled Plasma-mass Spectrometry Method in Normally Developed Children Aged Less than 7 Years in Masan City (Korea)

ABSTRACT

PURPOSE: Iodine is an essential component of thyroid hormones, and iodine deficiency disorder, including mental retardation, hypothyroidism, goiter, cretinism, and developmental abnormalities is the world's greatest single cause of preventable brain damage. Urine iodine (UI) is a sensitive indicator of recent changes in iodine intake. The objective of this study was to analyze the UI concentration in children younger than 7 years of age. METHODS: This population-based cross sectional study was conducted in four nurseries, three kindergartens, and the Samsung Changwon Hospital of Masan city in Korea from February to June 2010. Three hundred eighty-one samples of urine and 345 simple questionnaires were collected from normally developed preschool children less than 7 years of age. Urine samples were transferred to the Department of Laboratory Medicine at Samsung Seoul Hospital to measure UI concentration by inductively coupled plasma-mass spectrometry (ICP-MS) method. RESULTS: The median UI concentration was 327.9 microg/L (range 26.3-19,152.0 microg/L). There were 38 (10.0%) children with insufficient iodine intake (UI less than 100 microg/L). Of all children tested, the percentage of children with excessive iodine intake (UI over 300 microg/L) was 54.9%, and extremely high values exceeding 1,000 microg/L were found in 15.5% of investigated children. There was a significant difference in the median UI concentration between three age groups (P<0.05) but no significance between males and females. CONCLUSION: After measuring UI concentration, we report excessive iodine intake in preschool children less than 7 years of age in Masan city, Korea. In our population sample, we found that 10.0% of children had iodine deficiency.