Normal Reference for Bone Density in Healthy Chinese Children

Abstract 

An ethnicity- and gender-specific normal reference database is necessary for the clinical dual-energy X-ray absorptiometry (DXA) assessment of skeletal status in Chinese children. We used a Lunar Prodigy DXA densitometer to measure bone mineral density (BMD), bone mineral content (BMC), and bone area (BA) at total body and subcranial skeleton for 877 healthy Chinese children (505 boys, 372 girls) aged 5–13yr. The height-for-age, BA-for-height, and BMC-for-BA percentile curves were developed using the LMS method (L, power in Box-Cox transformation; M, median; S, coefficient of variation). We found that total body BMD and subcranial skeleton BMD were highly correlated (r=0.701–0.949), and that total body BMD was significantly higher than subcranial skeleton BMD for each gender and age group (p<0.001). No gender differences in total body and subcranial skeleton BMD were found. Total body lean mass correlated highly with total body BMC and subcranial skeleton BMD and BMC (boys: r=0.888–0.953, girls: r=0.917–0.967) and moderately with total body BMD (boys: r=0.684, girls: r=0.777). The head region accounted for 16–52% and 16–49% of the total body BMC in boys and girls, respectively, and the percentages were negatively correlated with age (boys: r=−0.824, girls: r=−0.864) and height (boys: r=−0.911, girls: r=−0.922). Regression analyses showed that age explained more variance in subcranial skeleton BMD (boys: R²=0.641, girls: R²=0.685) than in total body BMD (boys: R²=0.387, girls: R²=0.472). In summary, we have presented an ethnicity- and gender-specific densitometric normal reference database for Chinese children aged 5–13yr. It should allow for an appropriate clinical assessment of total body bone density in Chinese children as measured by the Lunar Prodigy DXA densitometer.

Key Words: Bone mineral density, children, Chinese, DXA, normal reference