FGF23 and calcification: The mechanism underlining arterial stiffness in the CKD population is complex and can be attributed to the progression of vascular calcification, owing to Chronic Kidney Disease–Mineral and Bone Disorder (CKD-MBD) and an imbalance between factors promoting calcification i.e., phosphate, parathormone, fibroblast growth factor-23 (FGF−23), and calcification inhibitors (e.g., fetuin-A) [18].