Data from: Vitamin D status among Thai school children and the association with 1,25-dihydroxyvitamin D and parathyroid hormone levels

In several low latitude countries, vitamin D deficiency is emerging as a public health issue. Adequate vitamin D is essential for bone health in rapidly growing children. In the Thai population, little is known about serum 25-hydroxyvitamin D [25(OH)D] status of infants and children. Moreover, the association between 25(OH)D and the biological active form of 1,25-dihydroxyvitamin D [1,25(OH)]2D is not clear. The specific aims of this study were to characterize circulating serum 25(OH)D, 1,25(OH)2D and their determinants including parathyroid hormone (PTH), age, sex, height and body mass index (BMI) in 529 school-aged Thai children aged 6–14 y. Adjusted linear regression analysis was performed to examine the impact of age and BMI, and its interaction with sex, on serum 25(OH)D concentrations and 1,25(OH)2D concentrations. Serum 25(OH)D, 1,25(OH)2D and PTH concentrations (geometric mean ± geometric SD) were 72.7±1.2 nmol/L, 199.1±1.3 pmol/L and 35.0±1.5 ng/L, respectively. Only 4% (21 of 529) participants had a serum 25(OH)D level below 50 nmol/L. There was statistically significant evidence for an interaction between sex and age with regard to 25(OH)D concentrations. Specifically, 25(OH)D concentrations were 19% higher in males. Moreover, females experienced a statistically significant 4% decline in serum 25(OH)D levels for each increasing year of age (P = 0.001); no decline was seen in male participants with increasing age (P = 0.93). When BMI, age, sex, height and serum 25(OH)D were individually regressed on 1,25(OH)2D, height and sex were associated with 1,25(OH)2D with females exhibiting statistically significantly higher serum 1,25(OH)2D levels compared with males (P<0.001). Serum 1,25(OH)2D among our sample of children exhibiting fairly sufficient vitamin D status were higher than previous reports suggesting an adaptive mechanism to maximize calcium absorption.

在多个低纬度国家，维生素D缺乏正逐渐成为一项公共卫生议题。充足的维生素D对快速生长发育期儿童的骨骼健康至关重要。在泰国人群中，目前对婴幼儿及儿童的血清25-羟基维生素D [25(OH)D] 水平状况尚缺乏了解。此外，25(OH)D与其生物活性形式1,25-二羟基维生素D [1,25(OH)2D] 之间的关联尚不明确。本研究的特定目标为，对529名6至14岁泰国学龄儿童的循环血清25(OH)D、1,25(OH)2D水平及其影响因素进行表征，其中影响因素包括甲状旁腺激素（PTH）、年龄、性别、身高以及体重指数（BMI）。本研究采用校正后的线性回归分析，探究年龄、BMI及其与性别的交互作用对血清25(OH)D和1,25(OH)2D浓度的影响。受试人群的血清25(OH)D、1,25(OH)2D及PTH浓度（几何均值±几何标准差）分别为72.7±1.2 nmol/L、199.1±1.3 pmol/L及35.0±1.5 ng/L。仅有4%的受试对象（529人中的21名）其血清25(OH)D水平低于50 nmol/L。研究发现，性别与年龄对25(OH)D浓度存在具有统计学意义的交互作用。具体而言，男性的25(OH)D浓度较女性高19%。此外，女性的血清25(OH)D水平随年龄每增长1岁即出现具有统计学意义的4%下降（P=0.001）；而男性的血清25(OH)D水平则未随年龄增长出现显著下降（P=0.93）。当分别以BMI、年龄、性别、身高及血清25(OH)D为自变量，对1,25(OH)2D进行回归分析时，身高与性别均与1,25(OH)2D水平存在关联，且女性的血清1,25(OH)2D水平显著高于男性（P<0.001）。本研究中维生素D状态较为充足的儿童群体，其血清1,25(OH)2D水平高于既往研究报道，这提示机体存在最大化钙吸收的适应性机制。