Moyer-Mileur L J, Xie B, Ball S D, Pratt T
Center for Pediatric Nutrition Research, Department of Pediatrics, University of Utah, Salt Lake City, UT 84132, USA.
J Musculoskelet Neuronal Interact. 2003 Mar;3(1):63-70.
Maximal bone acquisition in adolescent girls through dietary and lifestyle practices is advocated to prevent or minimize the development of osteoporosis and its associated complications in later life. Longitudinal investigations of bone acquisition in children and adolescents have utilized areal bone mineral density (BMD, mg/cm(2)) as a measure of bone mass and strength. Peripheral quantitative computed tomography (pQCT), which provides a three-dimensional display of data, separate analyses of bone compartments, and bone mass in terms of volumetric BMD (vBMD, mg/cm(3)), has recently been introduced for clinical use.
To assess the impact of a 12-month daily calcium supplement on total and trabecular bone acquisition as measured by pQCT in preadolescent girls.
Early adolescent Caucasian girls (aged 12 years, Tanner Stage 2) were enrolled in a randomized trial of daily calcium supplement (TX, 800 mg calcium carbonate and 400 IU vitamin D) or placebo (C). Body weight, height, and distal tibia measurements by pQCT were obtained at enrollment, 6 and 12 months. Pubertal status and physical activity records were assessed at baseline and 12 months. Three-day food intake records were completed every three months.
Seventy-one girls completed the 12-month trial (TX=35, C=36). No differences were found for age, weight, height, body mass index, pubertal maturation, or reported physical activity at enrollment or during the study. Average intakes during the study were 1524 mg calcium and 496 IU vitamin D (TX) versus 865 mg calcium and 160 IU vitamin D (C) per day. Baseline total bone values were similar, however, trabecular values were greater in TX girls despite randomization. Percent changes were calculated to adjust for baseline differences. Because of the small cortical thickness at the 10% site (mean values < 1.6 mm), cortical mass and density were not analyzed. The percent changes for trabecular bone mineral content (BMC, mg) and vBMD were significantly greater in TX girls (+4.1% BMC and +1.0% vBMD TX versus -1.6% BMC and -2.0% vBMD C, p<0.006; ANCOVA) after 12 months of supplement. Trabecular bone area (BA, cm(2)) and total bone change, however, did not differ between groups.
Daily calcium and vitamin D supplementation promotes greater trabecular BMC and vBMD acquisition in preadolescent girls. The single site selected for pQCT evaluation in this study did not allow evaluation of the cortical bone compartment. Future studies that utilize the pQCT technique need to incorporate multiple measurement sites to better assess total, cortical, and trabecular bone.
提倡青春期女孩通过饮食和生活方式的调整实现最大骨量获取，以预防或减少晚年骨质疏松症及其相关并发症的发生。儿童和青少年骨量获取的纵向研究一直将骨面积密度（BMD，mg/cm²）作为骨质量和强度的衡量指标。外周定量计算机断层扫描（pQCT）能够提供三维数据显示、对骨腔室进行单独分析，并以体积骨密度（vBMD，mg/cm³）来表示骨量，该技术最近已引入临床应用。
评估每日补充钙剂12个月对青春期前女孩经pQCT测量的总体骨量和小梁骨量获取的影响。
招募青春期早期的白人女孩（12岁，坦纳2期），进行每日补充钙剂（TX组，800mg碳酸钙和400IU维生素D）或安慰剂（C组）的随机试验。在入组时、6个月和12个月时，通过pQCT测量体重、身高和胫骨远端。在基线和12个月时评估青春期状态和身体活动记录。每三个月完成一次为期三天的食物摄入记录。
71名女孩完成了12个月的试验（TX组 = 35名，C组 = 36名）。在入组时或研究期间，两组在年龄、体重、身高、体重指数、青春期成熟度或报告的身体活动方面均未发现差异。研究期间的平均摄入量为每日1524mg钙和496IU维生素D（TX组），而C组为865mg钙和160IU维生素D。基线时总体骨值相似，然而，尽管进行了随机分组，TX组女孩的小梁骨值更高。计算百分比变化以调整基线差异。由于10%部位的皮质厚度较小（平均值 < 1.6mm），未对皮质骨质量和密度进行分析。补充12个月后，TX组女孩的小梁骨矿物质含量（BMC，mg）和vBMD的百分比变化显著更大（TX组BMC增加4.1%，vBMD增加1.0%，而C组BMC减少1.6%，vBMD减少2.0%，p < 0.006；协方差分析）。然而，两组之间的小梁骨面积（BA，cm²）和总体骨变化并无差异。
每日补充钙和维生素D可促进青春期前女孩获得更多的小梁骨BMC和vBMD。本研究中选择用于pQCT评估的单一部位无法对皮质骨腔室进行评估。未来利用pQCT技术的研究需要纳入多个测量部位，以更好地评估总体骨、皮质骨和小梁骨。
