Kindler JM, Kalkwarf HJ, Lappe JM, et al. - Researchers conducted this multicenter longitudinal study to develop age-, sex-, and population ancestry-specific reference ranges for ultradistal (UD) radius areal bone mineral density (aBMD) assessed by dual energy X-ray absorptiometry (DXA) and calculate Z-scores. They investigated tracking of UD radius aBMD Z-scores over 6 years and determined connections between UD radius aBMD Z-scores and other bone measures by DXA and peripheral quantitative computed tomography. In total, 2,014 (922 males, 22% African American) children ages 5 to 19 years at enrollment who partook in the Bone Mineral Density in Childhood Study. Findings suggested a strong association of UD radius aBMD Z-scores with distal radius trabecular bone density, with marginal confounding by stature. Such reference data may give a valuable resource for bone health assessment in children.