TNFRSF11B and Osteopenia: The ROC curve analysis showed that the best serum cutoff values of OPG to predict osteopenia + osteoporosis and osteoporosis alone of MHD patients were 388.38 pg/mL and 394.73 pg/mL, with AUCs of 0.920 (95% C.I., 0.834−0.970; p < 0.001) and 0.958 (95% C.I., 0.885−0.991; p < 0.001), respectively (Figure 3).