The application of other bone metabolism markers (e.g., β-CrossLaps (β-CTX), total procollagen type I amino-terminal propeptide (T-P1NP), osteocalcin (OC), and 25-hydroxyvitamin D (25OHD), etc.)in CKD is controversial, and there are few related studies. The gene discussed is CYP27A1; the disease is chronic kidney disease.