Department of Epidemiology, University of Michigan School of Public Health, Ann Arbor, MI, USA.
Eur J Clin Nutr. 2013 Jun;67(6):646-51. doi: 10.1038/ejcn.2013.56. Epub 2013 Mar 6.
Studies regarding the role of iron on linear growth have yielded heterogeneous results. Some trials indicate that iron supplementation of iron-replete infants leads to slower-length gain. However, little is known of the relation between iron status and linear growth in school-age children.
We quantified plasma ferritin, mean corpuscular volume (MCV), and hemoglobin in 2714 children aged 5-12 years at recruitment into a cohort study. Height was measured periodically for a median of 30 months. Height-for-age Z-scores (HAZ) were calculated using the World Health Organization growth reference. Mixed effects models with restricted cubic splines were used to construct population HAZ-for-age growth curves for sex- and age-specific quartiles of each iron status indicator.
Ferritin and MCV were each inversely related to attained HAZ among boys after the adjustment for baseline age, baseline body mass index-for-age Z-score and socioeconomic status. There was a decreasing monotonic relation between quartiles of ferritin and estimated change in HAZ from ages 6 to 14 years (P trend=0.001); boys in the 4th quartile experienced a HAZ change that was 0.46 Z lower than that of boys in the 1st quartile (P=0.0006). Similarly, we observed smaller HAZ change among boys in the highest quartile of MCV in comparison with those in the 1st quartile (P trend=0.001). Hemoglobin was not related to linear growth in boys. None of the iron-status indicators were associated with linear growth in girls.
Higher iron status, as indicated by ferritin and MCV, is related to slower linear growth in iron-replete school-age boys.
关于铁对线性生长作用的研究结果存在差异。一些试验表明，铁补充剂会使铁充足的婴儿生长速度减慢。然而，对于学龄儿童的铁状态与线性生长之间的关系知之甚少。
我们在一项队列研究中招募了 2714 名年龄在 5-12 岁的儿童，测量了他们的血浆铁蛋白、平均红细胞体积（MCV）和血红蛋白。中位数为 30 个月定期测量身高。使用世界卫生组织生长参考值计算身高年龄 Z 分数（HAZ）。使用受限立方样条的混合效应模型构建了按性别和年龄特异性四分位数划分的每个铁状态指标的人群 HAZ 年龄生长曲线。
在调整基线年龄、基线体重指数年龄 Z 分数和社会经济地位后，铁蛋白和 MCV 均与男孩的 HAZ 呈负相关。铁蛋白四分位数与 6-14 岁 HAZ 变化之间存在递减的单调关系（趋势 P=0.001）；第 4 四分位的男孩的 HAZ 变化比第 1 四分位的男孩低 0.46 Z（P=0.0006）。同样，我们观察到 MCV 最高四分位的男孩的 HAZ 变化比第 1 四分位的男孩小（趋势 P=0.001）。血红蛋白与男孩的线性生长无关。在女孩中，没有任何铁状态指标与线性生长有关。
铁蛋白和 MCV 等较高的铁状态与铁充足的学龄期男孩的线性生长速度较慢有关。
