In a cohort study including 1,026 non-dialysis patients across all CKD stages, Ureña-Torres et al. showed that 25(OH)-VD ≤ 15 ng/mL was associated with high serum bone-specific alkaline phosphatase (BALP) and C-terminal cross-linked collagen type I telopeptides (CTX), both circulating bone remodeling biomarkers [91]. Here, CYP27A1 is linked to chronic kidney disease.