Abrams Steven A, Griffin Ian J, Hawthorne Keli M, Gunn Sheila K, Gundberg Caren M, Carpenter Thomas O
United States Department of Agriculture/Agricultural Research Service, Children's Nutrition Research Center, 1100 Bates Street, Houston, Texas 77030, USA.
J Clin Endocrinol Metab. 2005 Oct;90(10):5576-81. doi: 10.1210/jc.2005-1021. Epub 2005 Aug 2.
Evidence suggests that vitamin D status in adults, as assessed by serum 25-hydroxyvitamin D (25-OHD), is positively associated with calcium absorption fraction and inversely associated with serum PTH. Few comparable pediatric data exist.
The objective of this study was to evaluate the relationships among vitamin D status, PTH, and calcium absorption in midpubertal boys and girls.
Calcium absorption was measured as part of an evaluation of the effects of prebiotics (inulin-type fructans) using a stable isotope method in 93 young adolescents, 12.7 +/- 1.0 yr of age, receiving diets averaging approximately 900 mg/d calcium.
A significant positive relation to calcium absorption was found for serum 1,25-dihydroxyvitamin D (P = 0.048) and PTH (P = 0.007), but not for 25-OHD (P = 0.77). PTH was significantly inversely related to 25-OHD and was positively related to serum 1,25-dihydroxyvitamin D and osteocalcin. PTH was marginally significantly inversely related to lumbar spinal, but not whole body, bone mineral density.
These data suggest that in adolescents, especially in the presence of vitamin D insufficiency, PTH secretion increases to adapt to higher rates of bone formation associated with growth. This results in higher serum 1,25(OH)2D concentrations and increased calcium absorption results. Vitamin D status, as reflected by the serum 25-OHD level, is not closely related to calcium absorption. Whether adaptation to low serum 25-OHD is adequate under physiologically stressful situations, including those leading to very low serum 25-OHD levels, is unknown.
有证据表明，通过血清25-羟基维生素D（25-OHD）评估的成年人维生素D状态与钙吸收分数呈正相关，与血清甲状旁腺激素（PTH）呈负相关。几乎没有可比的儿科数据。
本研究的目的是评估青春期中期男孩和女孩的维生素D状态、PTH和钙吸收之间的关系。
在一项使用稳定同位素方法评估益生元（菊粉型果聚糖）效果的研究中，对93名年龄为12.7±1.0岁、平均每日钙摄入量约为900mg的青少年进行了钙吸收测量。
血清1,25-二羟基维生素D（P = 0.048）和PTH（P = 0.007）与钙吸收呈显著正相关，但25-OHD与钙吸收无显著相关性（P = 0.77）。PTH与25-OHD呈显著负相关，与血清1,25-二羟基维生素D和骨钙素呈正相关。PTH与腰椎骨密度呈边缘显著负相关，但与全身骨密度无显著相关性。
这些数据表明，在青少年中，尤其是在维生素D不足的情况下，PTH分泌增加以适应与生长相关的更高骨形成率。这导致血清1,25(OH)2D浓度升高，钙吸收增加。血清25-OHD水平所反映的维生素D状态与钙吸收没有密切关系。在生理应激情况下，包括那些导致血清25-OHD水平极低的情况，对低血清25-OHD的适应性是否足够尚不清楚。
