Serum Osteoprotegerin Level Is Negatively Associated with Bone Mineral Density in Patients Undergoing Maintenance Hemodialysis

Background and Objectives: Osteoprotegerin (OPG), a potent osteoclast activation inhibitor, decreases bone resorption and plays a role in mediating bone mineral density (BMD). Our aim was to evaluate the relationship between BMD and serum OPG in maintenance hemodialysis (MHD) patients. Materials and Methods: Fasting blood samples were obtained from 75 MHD patients. BMD was measured by dual-energy X-ray absorptiometry in lumbar vertebrae (L2-L4). The WHO classification criteria were applied to define osteopenia and osteoporosis. A commercial enzyme-linked immunosorbent assay was used to measure serum OPG values. Results: Among all MHD patients, seven (9.3%) and 20 patients (26.7%) were defined as osteoporosis and osteopenia, respectively. Female patients had lower lumbar BMD than males (p = 0.002). Older age (p = 0.023), increased serum OPG (p < 0.001) urea reduction rate (p = 0.021), Kt/V (p = 0.027), and decreased body mass index (p = 0.006) and triglycerides (p = 0.020) were significantly different between the normal, osteopenia, and osteoporosis groups. Lumbar spine BMD was positively correlated with body mass index (BMI) (p < 0.001) but negatively correlated with OPG (p < 0.001) and age (p = 0.003). After grouping patients into T scores < -1 and < -2.5, female sex and OPG (adjusted odds ratio [aOR] 1.022, 95% confidence interval [C.I.] 1.011-1.034, p < 0.001) were predictors of T scores < -1, whereas only OPG was predictive of T scores < -2.5 (aOR 1.015, 95% C.I. 1.005-1.026, p = 0.004) by multivariate stepwise logistic regression analysis. The areas under the curve for predicting T scores < -1 or < -2.5 were 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. Conclusions: Increased serum OPG negatively correlated with lumbar BMD and could be a potential biomarker predictive of osteoporosis in MHD patients.