Reference values for the indicators of skeletal and muscular status of healthy Polish children

Dual-energy X-ray absorptiometry (DXA) results are affected by the growth- and maturation-based anthropometric variances during childhood and adolescence. To address this issue, anthropometric variables were implemented to normative DXA values for the total body (TB) and lumbar spine (S) data obtained from a cross-sectional sample of 562 healthy Caucasian children (278 females) aged 5 to 18 yr who were measured using a pencil-beam DXA device (DPX-L; GE Lunar). Across age or body height (BH) groups, female and male values for TB bone mineral content (TBBMC) (g), TB; bone mineral density (TTBMD) (g/cm(2)), SBMC (g), SBMD (g/cm(2)), lean body mass (LBM) (g), TBBMD/LBM (g/g), and SBMC/LBM [(g/g) x 100)] were assessed and compared using ANOVA and t-tests. There was no gender difference in TBBMC until age 16 and in TBBMD until age 17; thereafter, male values were significantly higher. At 12 to 13 yr of age, female SBMD values were significantly higher than male. The BH matching revealed lack of major gender-related differences in TBBMC or TBBMD values across whole height range, whereas at heights of 150 to 175 cm, females had generally higher values of SBMC and SBMD than male counterparts. Further, the LBM values and calculated TBBMC/LBM and SBMC/LBM ratios were considered as the muscle and muscle-bone indicators, respectively. The muscle-bone relationship analysis using LBM and TBBMC/LBM and SBMC/LBM values revealed age- and BH-related differences between genders. At LBM values of 32 kg and above and ages 14 yr and above for the whole skeleton as well as 12 yr and above for spine segment, females accrued significantly more BMC for the LBM unit than males. In order to properly assess children who might be at risk for low bone mass, we provide reference values for BMC and BMD of usually studied sites, expanded by muscle-bone relationship indicators owing to reduced diagnostic errors and distinguished bone disorders.