Reference centiles of bone mineral density, and body composition of lower limbs in children and adolescents for Hologic DXA Discovery model A

Background: Regional Dual-energy X-ray absorptiometry (DXA) assessments are useful for patients where whole body measurements are not feasible due to positioning difficulties because of anatomic anomalies (e.g. severe scoliosis) and artifacts due to neuroorthopedic hardware. Until now, there is a lack of reference centiles of bone mineral density and body composition of lower limbs for the DXA device Hologic Discovery model A densitometer. The study aimed to generate age-and sex specific reference centiles of bone mineral content (BMC), bone mineral density (BMD), lean body mass (LBM), and fat mass (FM) of the lower limbs of children and adolescents of Hologic DXA system (Discovery model A). Methodology: Data from children and adolescents aged 8-20 years of the National Health and Nutrition Examination Survey (NHANES) of the years 2015-2018 were used to create age-specific and sex-specific reference centiles. Study population was subdivided into three ethnic groups (non-Hispanic Black, non-Hispanic White and Mexican-American). The LMS method was used to calculate the reference centiles. Study population was adjusted concerning the BMI. Results: A total of DXA scans of 769 non-Hispanic Black children (386 females), 937 non-Hispanic White children (447 females) and 692 Mexican-American children (370 females) were used to calculate age-specific and sex-specific reference curves. 881 DXA scans had to be excluded because of extreme BMI values of the study population, leaving 513 non-Hispanic Black (205 females), 346 Mexican-American children (179 females), 658 Non-Hispanic White (282 females) for statistical analysis and creating age-and sex specific reference centiles after BMI adjustment. Conclusions: We presented pediatric reference centiles for regional bone mineral density, bone mineral content, lean body mass and fat mass of the lower limbs which were age-and sex-specific for three ethnic groups (Mexican-American, non-Hispanic Black and non-Hispanic-White). The reference centiles can be used for the Hologic DXA system Discovery model A with the software version 3.2