Spinal bone mineral density in 335 normal and obese children and adolescents: evidence for ethnic and sex differences.

Spinal bone mineral density (BMD) and anthropometric measures were studied in 312 nonobese and 23 obese black, white and Hispanic children and adolescents age 5.00-18.99 years. In adolescents BMD correlated with age, weight, height, fat-free density, body mass index, and midarm circumference. Utilizing the entire group of 312 nonobese subjects, mean Z scores were calculated for comparison versus reference subgroups for bone mineral density index (BMDI, BMD/weight). BMDI was greater for black than for white and Hispanic children and adolescents across all ages studied. Female adolescents accumulated spinal mineral more rapidly than male adolescents. Black males had greater mineral than white and Hispanic males. Differences in BMDI between subgroups could not be explained by differences in body weight or spinal vertebral size. BMDI proved a more sensitive measure for comparing subgroups than did BMD. The study provides normative data and a quantitative methodology for analyzing differences in spinal mineral between groups of children and adolescents.