Evaluation of novel bone metabolism markers in kidney transplant recipients

Abstract

Abstract Introduction: Immunosuppressive therapies, persistent hyperparathyroidism, and other risk factors influence mineral and bone disorder (MBD) after kidney transplantation. However, little is known about their effect on bone metabolism biomarkers. Therefore, we aimed to understand how kidney transplant affects these markers in comparison to patients on hemodialysis and healthy individuals. Methods: This is a cross-sectional study with three groups: kidney transplantation patients, patients on hemodialysis, and healthy controls. Plasma concentrations of Dickkopf-related protein 1 (DKK1), osteoprotegerin (OPG), osteocalcin (OC), osteopontin (OPN), sclerostin (SOST), and fibroblast growth factor 23 (FGF-23) were measured in these three groups. Associations between the measurements of these molecules with clinical and laboratory data were evaluated. Results: A total of 114 patients were included in the study. Transplant recipients had significantly lower levels of DKK1 (p < 0.001), OPG (p < 0.001), OC (p < 0.001), OPN (p = 0.001), OST (p < 0.001), and FGF-23 (p < 0.001) when compared to patients on hemodialysis. In transplant recipients, alkaline phosphatase levels positively correlated with OPN (r = 0.572, p < 0.001), while FGF-23 was negatively correlated with 25-hydroxyvitamin D (r = -0.531; p = 0.019). The bone biomarkers panel was able to successfully predict hypercalcemia (AUC 0.852; 95%CI = 0.679–1.000) and dyslipidemia (AUC 0.811; 95%CI 0.640–0.982) in transplant recipients. Conclusion: Our findings showed a reduction in bone metabolism markers, DKK1, OPG, OC, OPN, and SOST after kidney transplantation. Kidney transplantation modulates MBD markers, suggesting a significant improvement of MBD associated with end-stage kidney disease.