Bone Mineral Accretion in Young Children

描述（由申请人提供）：患有慢性疾病的儿童存在骨强度降低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至20岁的儿童骨矿物质状态受损（年龄骨密度低），并优化他们的医疗护理。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5岁以下幼儿的骨骼健康，尽管许多临床疾病（如早产、胃肠道和神经肌肉疾病）威胁着这一年龄范围内的骨骼健康。幼儿期不同于其他发育阶段。在年龄较大的儿童中，在解释骨骼测量时需要考虑生长状况和瘦质量，但在儿童早期，这些影响尚不清楚。大肌肉运动技能、运动和身体活动的显著变化也发生在儿童早期。生长骨骼的机械负荷促进骨矿物质的积累。了解生长、身体组成、运动技能发展和身体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

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.