Department of Human Nutrition, University of Otago, Dunedin 9054, New Zealand.
Nutr J. 2012 May 8;11:31. doi: 10.1186/1475-2891-11-31.
Insufficient iodine in children's diets is of concern because thyroid hormones are needed for normal growth and development, particularly of the brain. This study aimed to carry out a comprehensive assessment of the iodine status of New Zealand schoolchildren using a range of biochemical indices suitable for populations (i.e. urinary iodine concentration) and individuals (i.e. thyroid hormones).
The New Zealand National Children's Nutrition Survey was a cross-‒sectional survey of a representative sample of schoolchildren aged 5-‒14 years. Children were asked to provide a casual urine sample for the determination of urinary iodine concentration (UIC) and a blood sample for the determination of thyroglobulin (Tg), Thyroid Stimulating Hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3).
The median UIC was 68 μg/L (n = 1153), which falls between 50-‒99 μg/L indicative of mild iodine deficiency. Furthermore, 29% of children had an UIC <50 μg/L and 82% had an UIC <100 μg/L. The median Tg concentration was 12.9 μg/L, which also falls between 10.0-‒19.9 μg/L indicative of mild iodine deficiency. The Tg concentration of children with an UIC <100 μg/L was 13.9 μg/L, higher than the 10.3 μg/L in children with an UIC >100 μg/L (P = 0.001). The mean TSH (1.7 mU/L), fT4 (14.9 pmol/L), and fT3 (6.0 pmol/L) concentrations for these mildly iodine deficient New Zealand children fell within normal reference ranges.
The UIC and Tg concentration indicate that New Zealand schoolchildren were mildly iodine deficient according to WHO/UNICEF/ICCIDD, and both are suitable indices to assess iodine status in populations or groups. The normal concentrations of TSH, fT4 and fT3 of these children suggest that these thyroid hormones are not useful indices of mild iodine deficiency.
儿童饮食中碘摄入不足令人担忧，因为甲状腺激素是正常生长和发育所必需的，尤其是大脑的发育。本研究旨在使用一系列适合人群（即尿碘浓度）和个体（即甲状腺激素）的生化指标，对新西兰学童的碘状况进行全面评估。
新西兰全国儿童营养调查是一项针对 5-14 岁代表性学童样本的横断面调查。要求儿童提供一份随意尿液样本，用于测定尿碘浓度（UIC），并提供一份血液样本，用于测定甲状腺球蛋白（Tg）、促甲状腺激素（TSH）、游离甲状腺素（fT4）和游离三碘甲状腺原氨酸（fT3）。
UIC 的中位数为 68μg/L（n=1153），处于 50-99μg/L 之间，表明存在轻度碘缺乏。此外，29%的儿童 UIC<50μg/L，82%的儿童 UIC<100μg/L。Tg 浓度的中位数为 12.9μg/L，也处于 10.0-19.9μg/L 之间，表明存在轻度碘缺乏。UIC<100μg/L 的儿童 Tg 浓度为 13.9μg/L，高于 UIC>100μg/L 的儿童的 10.3μg/L（P=0.001）。这些轻度碘缺乏的新西兰儿童的平均 TSH（1.7mU/L）、fT4（14.9pmol/L）和 fT3（6.0pmol/L）浓度均在正常参考范围内。
根据世卫组织/儿基会/国际碘缺乏病控制联盟的标准，UIC 和 Tg 浓度表明新西兰学童存在轻度碘缺乏，这两种指标均适合用于评估人群或群体的碘状况。这些儿童 TSH、fT4 和 fT3 的正常浓度表明，这些甲状腺激素不是轻度碘缺乏的有用指标。
