How Kidney Disease Silently Calcifies Your Arteries and What Biomarkers Reveal It

Cardiovascular disease is the leading killer of CKD patients, yet traditional risk factors like hypertension and diabetes explain only part of the excess mortality. In hemodialysis patients, five-year mortality exceeds 50% when preexisting CVD is present, and vascular calcification (VC) is a central, underappreciated driver. This 2025 review from Romanian nephrology centers systematically examined the pathophysiology and biomarker landscape of VC in CKD and hemodialysis across 65 peer-reviewed studies.

The review establishes that VC is a cell-mediated, actively regulated process rather than a passive mineral precipitation event. Vascular smooth muscle cells (VSMCs), under pressure from hyperphosphatemia, oxidative stress, and inflammation, undergo osteoblastic transformation driven by transcription factors Runx2, BMP2, and Msx2. They release matrix vesicles and apoptotic bodies that serve as hydroxyapatite nucleation sites, predominantly in the arterial media. Simultaneously, protective calcification inhibitors—matrix Gla protein (MGP) and fetuin-A—are suppressed, particularly in the context of vitamin K deficiency, which is nearly universal in dialysis patients. Wnt/β-catenin, Notch, and NF-κB signaling pathways further reinforce this pro-calcific state, while epigenetic changes including microRNA dysregulation lock VSMCs into an osteogenic phenotype.

Mineral dysregulation through the CKD–MBD axis compounds the problem. Rising FGF23 levels—an early renal stress response—coincide with declining Klotho expression, impairing phosphate excretion and vitamin D activation. Secondary hyperparathyroidism elevates PTH, accelerating bone resorption and releasing calcium and phosphate into the circulation. Uremic toxins such as indoxyl sulfate and TMAO, poorly cleared even by hemodialysis, add pro-inflammatory and pro-atherogenic insults that impair endothelial nitric oxide production and directly promote calcification.

Among emerging biomarkers, desphospho-uncarboxylated MGP (dp-ucMGP) stands out as the most mechanistically grounded marker of VC activity. It reflects the fraction of MGP that is both unphosphorylated and uncarboxylated—essentially inactive—due to vitamin K deficiency. Elevated dp-ucMGP correlates with greater calcification burden and cardiovascular risk in CKD and HD cohorts. Osteocalcin (OC), another vitamin K–dependent protein, provides complementary insight into bone–vascular crosstalk and bone turnover status. Intact PTH (iPTH) remains the standard tool for assessing secondary hyperparathyroidism and guiding mineral management, though its relationship with VC is bidirectional and complex. The review notes that all three biomarkers face challenges including assay variability, renal clearance effects, and clinical heterogeneity that limit direct comparability across studies.

The authors advocate for a multimarker clinical approach that integrates dp-ucMGP, OC, and iPTH alongside imaging modalities to better stratify cardiovascular risk and guide interventions such as vitamin K supplementation, phosphate binders, and calcimimetics. They emphasize that no single biomarker is sufficient and that therapeutic decisions must account for individual mineral metabolism profiles. The review calls for prospective validation studies with standardized assays before these biomarkers can be adopted into routine clinical guidelines.