Bone Mineral Accretion in Young Children

描述(由申请人提供)：患有慢性疾病的儿童有骨质强度受损和骨折易感性增加的风险。最近开发的参考数据使临床医生能够识别5-20岁骨矿状态受损的儿童(年龄骨密度低)，并优化他们的医疗保健。一个明显的缺陷是，由于缺乏适当的骨密度参考数据，无法评估幼儿的骨健康，尽管许多临床疾病(例如，早产、胃肠道和神经肌肉疾病)威胁着这一年龄段的骨健康。幼儿期与其他发展阶段不同。在年龄较大的儿童中，解释骨骼测量时需要考虑生长状况和瘦体重的必要性已经得到证实，但在儿童早期，这些影响是未知的。粗大运动技能、运动和体力活动的显著变化也发生在儿童早期。骨骼生长过程中的机械负荷会促进骨矿物质的积累。了解生长、身体成分、运动技能发展和体力活动对幼儿骨积累的影响对于解释临床骨矿物质状态测量至关重要。这些特征通常在患有慢性疾病的幼儿中受到影响。这项研究的长期目标是 优化幼儿骨骼健康。这项纵向研究的目的是开发1-5岁儿童的局部和整体骨矿含量(BMC)和密度(ABMD)参考数据，以帮助识别有骨缺陷的幼儿，并确定影响该年龄段骨量增加的因素。这项纵向研究的目的是：(1)测试1-5岁健康儿童多个骨骼部位的BMC和aBMD的性别和祖先差异，并建立适当的参考曲线；(2)评估生长和身体组成的影响；(3)粗大运动技能和体力活动对骨矿状态和骨矿积累量的影响；(4)确定对幼儿骨状态的“跟踪”程度。有待检验的假设是：男性将比女性有更大的BMC和aBMD；黑人将比非黑人有更大的BMC和aBMD；生长状况更好、组织更瘦、粗大运动技能更高级、体力活动水平更高的儿童的骨矿状况和骨积累将更大；这项研究是独一无二的，因为以前没有研究涉及1-5岁儿童的这些问题。这项研究具有临床意义，因为研究结果将有助于对患有威胁骨骼健康的慢性疾病的儿童进行医疗护理，并将开发和验证该年龄段的骨和身体成分评估的新方法。它还将增加概括性知识，以加强对不断增长的骨骼及其与运动和躯体发育的关系的理解。由于不良的骨矿物质积累可能会产生终生后果，这项研究解决了骨质疏松症的主要公共健康问题。

DESCRIPTION (provided by applicant): Children with chronic medical conditions are at risk of compromised bone strength and increased fracture susceptibility. Recently developed reference data have enabled clinicians to identify children 5 to 20 y with compromised bone mineral status (low bone density for age) and optimize their medical care. A glaring deficit is the inability to evaluate bone health of young children < 5 y due to lack of appropriate bone density reference data, although numerous clinical conditions (e.g., prematurity, gastrointestinal and neuromuscular disorders) threaten bone health in this young age range. Early childhood differs from other developmental stages. In older children, the need to account for growth status and lean mass when interpreting bone measurements has been demonstrated, but in early childhood, these effects are unknown. Pronounced changes in gross motor skills, locomotion and physical activity also occur in early childhood. Mechanical loads on the growing skeleton promote bone mineral accrual. Understanding the impact of growth, body composition, motor skill development, and physical activity on bone accrual in young children is critical for interpretation of a clinical bone mineral status measurement. These characteristics are often affected in young children with chronic medical conditions. The long-term goal of this study is to optimize bone health of young children. The objectives of this longitudinal study are to develop regional and total body bone mineral content (BMC) and density (aBMD) reference data for children ages 1-5 y to aid identification of young children with bone deficits, and identify factor that influence bone accrual in this age group. The aims of this longitudinal study are: (1) test fo sex and ancestry differences in BMC and aBMD at multiple skeletal sites in healthy children ages 1 to 5 y, and create appropriate reference curves; (2) assess the influence of growth and body composition, and (3) gross motor skills and physical activity on bone mineral status and bone mineral accrual, and (4) determine the degree of "tracking" of bone status in young children. Hypotheses to be tested are: males will have greater BMC and aBMD than females; Blacks will have greater BMC and aBMD than non-blacks; bone mineral status and bone accrual will be greater in children with greater growth status and more lean tissue, more advanced gross motor skills, and higher physical activity levels; and BMC and aBMD z-scores will be positively correlated over 3 y. The study is unique since no previous studies have addressed these issues in children 1-5 y. It is clinically relevant as findings will facilitate medcal care of children with chronic medical conditions that threaten bone health, and it will develop and validate novel methods for bone and body composition assessment in this age range. It will also add generalizable knowledge to enhance understanding of the growing skeleton, and its relationship to motor and somatic development. Since poor bone mineral accrual can have lifelong consequences, this study addresses the major public health concern of osteoporosis.