Remer Thomas, Fonteyn Nadine, Alexy Ute, Berkemeyer Shoma
Research Institute of Child Nutrition, Department of Nutrition and Health, Dortmund, Germany.
Am J Clin Nutr. 2006 Mar;83(3):639-46. doi: 10.1093/ajcn.83.3.639.
Because worldwide iodine status (IS) depends on continuous fortification, the adequacy of IS needs to be regularly monitored.
Our study aimed to evaluate IS in a longitudinal sample of healthy schoolchildren who regularly used table salt iodized with 20 microg I/g.
Urine osmolality (Uosm) and 24-h urinary excretion rates of iodine (24-h UI), sodium, creatinine, and total urine volume (24-h Uvol) were measured in 1046 specimens that were collected at repeated intervals from 1996 to 2003 in a sample of 358 German children aged 6-12 y. Energy intake and food consumption were calculated from 3-d weighed dietary records that were collected in parallel to the urine samples.
During the 4-y period from 1996 to 1999, the median 24-h UI increased from 87 to 93 microg I/d (P = 0.017), whereas urinary iodine concentration (UIC), Uosm, and 24-h Uvol did not change significantly. Thereafter (from 2000 to 2003), UIC stagnated and Uosm decreased (P = 0.004), whereas 24-h Uvol (P = 0.008) and 24-h UI (P = 0.002) increased. The final median 24-h UI reached 120 microg I/d. Milk, fish, egg, and meat intakes and 24-h sodium excretion were all significant predictors of IS, with an almost doubled contribution from milk intake during the second 4-y period.
Our study shows a continuous improvement of IS in a longitudinal sample of German schoolchildren. This improvement was masked when UIC was used as an IS index, especially from 2000 to 2003 because of changes in hydration status. Thus, in research-oriented studies that focus on UIC measurements, hydration status can be a relevant confounder. Longitudinal analyses of 24-h UI in cohort studies may represent an alternative hydration status-independent tool to examine trends in IS and the contribution of relevant foods to IS.
由于全球碘营养状况（IS）依赖于持续的碘强化，因此需要定期监测碘营养状况是否充足。
我们的研究旨在评估定期食用含碘量为20微克/克碘盐的健康学童纵向样本中的碘营养状况。
在1996年至2003年期间，对358名6至12岁德国儿童的样本重复采集了1046份样本，测量了尿渗透压（Uosm）、24小时尿碘排泄率（24-h UI）、钠、肌酐和总尿量（24-h Uvol）。能量摄入和食物消耗根据与尿液样本同时收集的3天称重饮食记录进行计算。
在1996年至1999年的4年期间，24小时尿碘中位数从87微克/天增加到93微克/天（P = 0.017），而尿碘浓度（UIC）、尿渗透压和24小时尿量没有显著变化。此后（从2000年到2003年），尿碘浓度停滞不前，尿渗透压下降（P = 0.004），而24小时尿量（P = 0.008）和24小时尿碘（P = 0.002）增加。最终24小时尿碘中位数达到120微克/天。牛奶、鱼类、蛋类和肉类的摄入量以及24小时钠排泄量都是碘营养状况的重要预测因素，在第二个4年期间，牛奶摄入量的贡献几乎增加了一倍。
我们的研究表明，德国学童纵向样本中的碘营养状况持续改善。当将尿碘浓度用作碘营养状况指标时，这种改善被掩盖了，尤其是在2000年至2003年期间，这是由于水合状态的变化。因此，在以尿碘浓度测量为重点的研究性研究中，水合状态可能是一个相关的混杂因素。队列研究中对24小时尿碘的纵向分析可能是一种独立于水合状态的替代工具，用于研究碘营养状况的趋势以及相关食物对碘营养状况的贡献。
