Objective To analyze serum levels of bone metabolism markers in patients with chronic kidney disease (CKD).

Methods Totally 544 CKD patients visited in the department of nephrology the First Affiliated Hospital of Dalian Medical University and Dalian Firendship Hospital from 2014 to 2018 were selected as the cases and 577 healthy volunteers were recruited as the controls. Serum levels of bone metabolic markers in the cases and the controls were measured and the detection results of the cases at different CKD stage (stage I CDK CKD-1 – stage V CDK CKD-5) were compared to those of the controls.

Results Compared with that in the controls, decreased 25-hydroxyvitamin D (25(OH)D) was detected in the cases of CKD-1 – CKD-5 phase (all P < 0.05), especially in the cases of CKD-2, CKD-4, and CKD-5 (P < 0.01 for all). Increased serum N-terminal midfragment of osteocalcin (N-MID), total type I procollagen amino terminal prolongation peptide (tPINP), and calcitonin (CT) were detected in the cases of CKD-4 (P < 0.05 for all) and in the cases of CKD-5 (P < 0.01). Significantly increased specific sequence of β-collagen (β-CTX) was detected in the cases of CKD-4 and CKD-5 (both P < 0.01). Correlation analyses revealed that 25(OH)D was positively correlated with calcium (Ca) and alkaline phosphatase (ALP) in the cases (r > 0, P < 0.01); N-MID, β-CTX, and CT were positively correlated with phosphorus (P) and parathyroid hormone (iPTH) (r > 0, P < 0.01); tPINP was positively correlated with Ca (r > 0, P < 0.01) and CT was correlated with Ca reversely (r < 0, P < 0.05).

Conclusion Serum 25(OH)D level is lower in all CKD patients than in healthy people; but serum N-MID increased obviously in stage VI – stage V CKD patients.