Pediatric Reference Ranges for Ultradistal Radius Bone Density: Results from the Bone Mineral Density in Childhood Study.

Abstract

CONTEXT: The ultradistal (UD) radius is rich in trabecular bone and is easily measured by dual energy X-ray absorptiometry (DXA). UD radius areal bone mineral density (aBMD) may help identify trabecular bone deficits, but reference data are needed for research and clinical interpretation of this measure. OBJECTIVE: We developed age-, sex-, and population ancestry-specific reference ranges for UD radius aBMD assessed by DXA and calculated Z-scores. We examined tracking of UD radius aBMD Z-scores over 6 years and determined associations between UD radius aBMD Z-scores and other bone measures by DXA and peripheral quantitative computed tomography (pQCT). DESIGN: Multicenter longitudinal study. PARTICIPANTS: 2014 (922 males, 22% African American) children ages 5-19 years at enrollment who participated in the Bone Mineral Density in Childhood Study. MAIN OUTCOME MEASURE: UD radius aBMD. RESULTS: UD radius aBMD increased non-linearly with age (p<0.001) and tended to be greater in males vs. females (p=0.054). Age-, sex-, and ancestry-specific UD radius aBMD reference curves were constructed. UD radius aBMD Z-scores positively associated with Z-scores at other skeletal sites (r=0.54-0.64, all p<0.001) and pQCT measures of distal radius total volumetric BMD (r=0.68, p<0.001) and trabecular volumetric BMD (r=0.70, p<0.001), and was weakly associated with height Z-score (r=0.09, p=0.015). UD radius aBMD Z-scores tracked strongly over 6 years, regardless of pubertal stage (r=0.66-0.69; all p<0.05). CONCLUSION: UD radius aBMD Z-scores strongly associated with distal radius trabecular bone density, with marginal confounding by stature. These reference data may provide a valuable resource for bone health assessment in children.