Median urinary iodine concentration reflected sufficient iodine supply in neonates from Northeast Germany in 2005–2006

Purpose Data from recent adult studies suggest a decline of median urinary iodine concentrations (UIC) in Germany, but since 1996 no German study investigated UIC in neonates. The aim of our study was to investigate UIC and serum thyroid-stimulating hormone (TSH) levels in neonates from Germany. Methods We used data from 399 neonates, which were born between April 2005 and November 2006 in the Northeast of Germany. UIC were evaluated by a photometric procedure with Sandell and Kolthoff reaction and afterwards corrected to be comparable with an ICP-MS method. TSH was determined from capillary blood, which was taken within 5 days after birth, by DELFIA. Results Median UIC were 150 µg/L (25th percentile: 104 µg/L; 75th percentile: 196 µg/L) and differed between boys (153.3 µg/L) and girls (131.5 µg/L; p = 0.012). The prevalence of serum TSH levels > 5 mIU/L was 14%. Neonates from mothers with intake of iodine supplementation (150 µg/L) had significantly higher median UIC than neonates from mothers without iodine supplementation (132 µg/L; p = 0.011). Multivariable linear regression adjusted for sex and iodine supplementation of the mother revealed a significant association between UIC and log-transformed serum TSH levels ( β = 0.003: 95% confidence interval (CI) = 0.0001–0.005; p = 0.028). Conclusions Neonates in Northeast Germany did show a sufficient supply of iodine. This points towards the possibility of a sufficient iodine supply of neonates also in other regions of Germany, even though recent studies in adults may indicate mild iodine deficiency.