瘦体重的纵向变化可预测6至7岁时胫骨几何形态和矿化的外周定量CT测量结果。
Longitudinal changes in lean mass predict pQCT measures of tibial geometry and mineralisation at 6-7 years.
作者信息
Moon Rebecca J, Cole Zoe A, Crozier Sarah R, Curtis Elizabeth M, Davies Justin H, Gregson Celia L, Robinson Sian M, Dennison Elaine M, Godfrey Keith M, Inskip Hazel M, Cooper Cyrus, Harvey Nicholas C
机构信息
MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UK; Paediatric Endocrinology, University Hospital Southampton NHS Foundation Trust, Southampton SO16 6YD, UK.
MRC Lifecourse Epidemiology Unit, University of Southampton, Southampton General Hospital, Southampton SO16 6YD, UK; Rheumatology, Salisbury Hospital NHS Foundation Trust, Salisbury, UK.
出版信息
Bone. 2015 Jun;75:105-10. doi: 10.1016/j.bone.2015.02.015. Epub 2015 Feb 20.
BACKGROUND
Studies in childhood suggest that both body composition and early postnatal growth are associated with bone mineral density (BMD). However, little is known of the relationships between longitudinal changes in fat (FM) and lean mass (LM) and bone development in pre-pubertal children. We therefore investigated these associations in a population-based mother-offspring cohort, the Southampton Women's Survey.
METHODS
Total FM and LM were assessed at birth and 6-7 years of age by dual-energy x-ray absorptiometry (DXA). At 6-7 years, total cross-sectional area (CSA) and trabecular volumetric BMD (vBMD) at the 4% site (metaphysis) of the tibia was assessed using peripheral quantitative computed tomography [pQCT (Stratec XCT-2000)]. Total CSA, cortical CSA, cortical vBMD and strength-strain index (SSI) were measured at the 38% site (diaphysis). FM, LM and bone parameters were adjusted for age and sex and standardised to create within-cohort z-scores. Change in LM (ΔLM) or FM (ΔFM) was represented by change in z-score from birth to 7 years old and conditioned on the birth measurement. Linear regression was used to explore the associations between ΔLM or ΔFM and standardised pQCT outcomes, before and after mutual adjustment and for linear growth. The β-coefficient represents SD change in outcome per unit SD change in predictor.
RESULTS
DXA at birth, in addition to both DXA and pQCT scans at 6-7 years, were available for 200 children (48.5% male). ΔLM adjusted for ΔFM was positively associated with tibial total CSA at both the 4% (β=0.57SD/SD, p<0.001) and 38% sites (β=0.53SD/SD, p<0.001), cortical CSA (β=0.48SD/SD, p<0.001) and trabecular vBMD (β=0.30SD/SD, p<0.001), but not with cortical vBMD. These relationships persisted after adjustment for linear growth. In contrast, ΔFM adjusted for ΔLM was only associated with 38% total and cortical CSA, which became non-significant after adjustment for linear growth.
CONCLUSION
In this study, gain in childhood LM was positively associated with bone size and trabecular vBMD at 6-7 years of age. In contrast, no relationships between change in FM and bone were observed, suggesting that muscle growth, rather than accrual of fat mass, may be a more important determinant of childhood bone development.
背景
儿童期研究表明，身体组成和出生后早期生长均与骨矿物质密度（BMD）相关。然而，青春期前儿童脂肪量（FM）和瘦体重（LM）的纵向变化与骨骼发育之间的关系却鲜为人知。因此，我们在一项基于人群的母婴队列研究——南安普敦妇女调查中，对这些关联进行了调查。
方法
通过双能X线吸收法（DXA）在出生时和6至7岁时评估总FM和LM。在6至7岁时，使用外周定量计算机断层扫描[pQCT（Stratec XCT - 2000）]评估胫骨4%部位（干骺端）的总横截面积（CSA）和小梁体积骨密度（vBMD）。在38%部位（骨干）测量总CSA、皮质CSA、皮质vBMD和强度应变指数（SSI）。对FM、LM和骨参数进行年龄和性别校正，并进行标准化以创建队列内z评分。LM（ΔLM）或FM（ΔFM）的变化用从出生到7岁的z评分变化表示，并以出生时的测量值为条件。使用线性回归来探讨ΔLM或ΔFM与标准化pQCT结果之间的关联，包括相互调整前后以及线性生长情况。β系数表示预测变量每单位标准差变化时结果的标准差变化。
结果
200名儿童（48.5%为男性）有出生时的DXA数据，以及6至7岁时的DXA和pQCT扫描数据。校正ΔFM后的ΔLM与胫骨4%部位（β = 0.57SD/SD，p < 0.001）和38%部位的总CSA（β = 0.53SD/SD，p < 0.001）、皮质CSA（β = 0.48SD/SD，p < 0.001）和小梁vBMD（β = 0.30SD/SD，p < 0.001）呈正相关，但与皮质vBMD无关。在调整线性生长后，这些关系仍然存在。相比之下，校正ΔLM后的ΔFM仅与38%部位的总CSA和皮质CSA相关，在调整线性生长后变得不显著。
结论
在本研究中，儿童期LM的增加与6至7岁时的骨骼大小和小梁vBMD呈正相关。相比之下，未观察到FM变化与骨骼之间的关系，这表明肌肉生长而非脂肪量的增加可能是儿童期骨骼发育更重要的决定因素。
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