Vascular calcification in chronic kidney disease: are biomarkers useful for probing the pathobiology and the health risks of this process in the clinical scenario?

Patients with chronic kidney disease (CKD) are at a particularly high risk for cardiovascular disease. Vascular calcification (VC) is considered a cardiovascular risk marker, so in CKD patients screening for the presence of VC is suggested in current guidelines. VC is the result of both passive and active processes that involve a variety of proteins and factors. In the CKD population, numerous studies have identified circulating biomarkers potentially responsible for VC and have evaluated their link with this process. This narrative review, and an accompanying analysis performed on the Amiens CKD database, focuses on selected VC biomarkers-namely phosphate, fibroblast growth factor 23 (FGF23), osteopontin (OPN), osteoprotegerin (OPG), matrix Gla protein and fetuin A-all of which have been implicated as major players in VC in experimental studies in vitro or in animal models. None of the VC biomarkers considered in this review have qualified as a reliable predictor of meaningful clinical events or as a valid indicator of the risk of having VC. In the analysis based on the Amiens-CKD database, no biomarker outperformed age and the classical risk factors as a predictor of VC either in the aorta or in the coronaries. Well-designed clinical trials are now urgently needed to test the potential value of these biomarkers as a guide for interventions targeting VC.