Lumbar Spine Bone Mineral Apparent Density in Children: Results From the Bone Mineral Density in Childhood Study.

CONTEXT: Dual-energy X-ray absorptiometry (DXA) is a cornerstone of pediatric bone health assessment, yet differences in height-for-age confound the interpretation of areal bone mineral density (aBMD) measures. To reduce the confounding of short stature on spine bone density, use of bone mineral apparent density (BMAD) and height-for-age Z-score (HAZ)‒adjusted aBMD (aBMDHAZ) are recommended. However, spine BMAD reference data are sparse, and the degree to which BMAD and aBMDHAZ account for height-related artifacts in bone density remains unclear.

OBJECTIVE

We developed age-, sex-, and population ancestry‒specific spine BMAD reference ranges; compared height-adjustment methods in accounting for shorter stature; and assessed the stability of these measures over time.

DESIGN

Secondary analysis of data from a previous longitudinal study.

PARTICIPANTS

Children and adolescents aged 5 to 19 years at baseline (n = 2014; 922 males; 22% black) from the Bone Mineral Density in Childhood Study.

MAIN OUTCOME MEASURES: Lumbar spine BMAD and aBMDHAZ from DXA.

RESULTS

Spine BMAD increased nonlinearly with age and was greater in blacks and females (all P < 0.001). Age-specific spine BMAD z-score reference curves were constructed for black and non‒black males and females. Overall, both BMAD and aBMDHAZz scores reduced the confounding influence of shorter stature, but neither was consistently unbiased across all age ranges. Both BMAD and aBMDHAZz scores tracked strongly over 6 years (r = 0.70 to 0.80; all P < 0.001).

CONCLUSION

This study provided robust spine BMAD reference ranges and demonstrated that BMAD and aBMDHAZ partially reduced the confounding influence of shorter stature on bone density.