TNFRSF11B and Osteopenia: The RANKL/OPG ratio showed positive and significant correlation with BMI (r = 0.34, p < 0.05), T-score dual left (r = 0.37, p < 0.05), femoral neck left BMD (r = 0.36, p < 0.05), and femoral neck right BMD (r = 0.35, p < 0.05) in the osteopenia group.