Fibroblast Growth Factor 23 and Osteoprotegerin in Vascular Calcification among Patients without Advanced Chronic Kidney Disease.

Objective Vascular calcification is associated with poor cardiovascular outcomes. However, the significance of calcification-related biomarkers in patients without advanced chronic kidney disease (CKD) remains unclear. Methods We prospectively enrolled 68 patients who underwent coronary computed tomography angiography followed by coronary angiography. This study assessed serum fibroblast growth factor 23 (FGF-23), osteoprotegerin (OPG), and fetuin-A levels along with the calcification of the coronary arteries, aortic valve, aortic arch, and abdominal aorta. Patients on maintenance dialysis were excluded, and the renal function was predominantly preserved (median estimated glomerular filtration rate 67.9 mL/min/1.73 m2). Associations were examined using Spearman's ρ, and the discrimination of severe coronary artery calcification (CAC) (Agatston ≥400) was evaluated using a receiver operating characteristic (ROC) curve analysis. Results CAC was correlated with FGF-23 (ρ=0.379, p=0.002), but not with fetuin-A or OPG. FGF-23 was also associated with the aortic arch (ρ=0.284, p=0.019), abdominal aortic calcification (ρ=0.311, p=0.010), and left ventricular mass index (ρ=0.425, p<0.001). For severe CAC, OPG showed the highest, albeit modest, discrimination (area under the ROC curve 0.69, 95% confidence interval 0.56-0.82; Youden cutoff 9.47), but it was not independently associated after adjusting for age. All biomarkers showed a weak association with aortic valve calcification. Conclusion In patients without advanced CKD, FGF-23 is associated with systemic vascular calcification and left ventricular remodeling, whereas OPG provides only a modest unadjusted discrimination for severe CAC and does not add to age. These findings suggest a limited, context-dependent role for these biomarkers, and underscore the need for larger, externally validated studies.