ASSOCIATION BETWEEN SYSTEMIC AND REGIONAL FAT-MUSCLE RATIO AND BONE METABOLISM IN ADOLESCENTS

Objective: To analyze the association between systemic and regional fat-muscle ratio (FMR) and serum osteocalcin (OC) and C-terminal peptide (CTX) in adolescents. Design and method: The stratified cluster sampling method was adopted to select 2,698 children and adolescents aged 12 to 18 years from junior and senior high schools in Yinchuan City. The bioelectrical impedance analysis was used to measure the fat and muscle mass of the whole body, upper limbs, lower limbs and trunk of the subjects, and calculate the whole-body fat-muscle ratio (FMR), arm fat-muscle ratio (AFMR), leg fat-muscle ratio (LFMR) and trunk fat-muscle ratio (TFMR). Regression analysis and restricted cubic splints were used to assess the linear and nonlinear relationships of systemic and local FMR with OC and CTX. Results: After adjusting confounding factors, FMR, LMR and TMR were positively correlated with OC in adolescents, and the same results were observed in girls. FMR was negatively correlated with CTX. FMR, AFMR, LMR and TMR were negatively correlated with CTX in girls after stratification by gender. The quartiles of FMR, AFMR, LMR and TMR were not associated with OC and CTX in the total population. After stratification by gender, the possibility of increasing OC level in the highest quartile of TMR in girls was 0.62 times that in the lowest quartile, and the possibility of increasing CTX level in the third quartile of AFMR in boys was 0.26 times that in the lowest quartile. Compared with the lowest quartile, the CTX content of the highest quartile of AFMR in girls decreased. The results of restricted cubic spline showed that there was a linear relationship between FMR, AFMR, LMR, TMR and OC (all Pgeneral trend<0.001, Pnon-linear>0.05), and there was a nonlinear dose-response relationship between AFMR and CTX (Pgeneral trend <0.001, Pnon-linear <0.05). Conclusions: The increased levels of FMR, LMR and TMR in adolescents increase the content of OC, and the increased level of FMR decreases the content of CTX. There are gender differences in the relationship between systemic and local FMR and OC and CTX in adolescents.