Association of Bone Turnover Markers and Gla Rich Protein with Pelvic Calcification Severity and Clinical Outcomes in Kidney Transplant Recipients: A Prospective Single-Center Study.

Background: Chronic kidney disease-mineral and bone disorder contributes to vascular calcification in kidney transplant recipients. However, the relationship between circulating bone turnover markers, Gla-rich protein (GRP), pelvic arterial calcification, and post-transplant outcomes remains uncertain. Methods: In this prospective single-centre study, 79 kidney transplant recipients underwent pre-transplant assessment of serum calcium, phosphate, alkaline phosphatase, parathyroid hormone, osteoprotegerin (OPG), receptor activator of nuclear factor kappa-B ligand (RANKL), and GRP. Pelvic arterial calcification was quantified using a validated CT-based scoring system. Associations between biomarkers, pelvic calcification severity, graft function, graft survival, patient survival, and major adverse cardiovascular events were evaluated. Results: Serum calcium was associated with serum creatinine (p = 0.039), and serum phosphate was associated with MAG-3 clearance (p = 0.009). OPG concentrations were significantly higher in patients receiving haemodialysis than in those receiving peritoneal dialysis (p = 0.021). No significant associations were observed between pelvic arterial calcification severity and circulating OPG, RANKL, or GRP concentrations. Furthermore, in univariable Cox proportional hazards models, none of the investigated biomarkers was significantly associated with graft or patient survival. Conclusions: Circulating OPG, RANKL, and GRP were not associated with pelvic arterial calcification, graft or patient survival. Larger multicentre studies with longer follow-up are warranted to clarify the prognostic value of these biomarkers.