The levels of bone turnover markers and parathyroid hormone and their relationship in chronic kidney disease

Chronic kidney disease-mineral bone disease (CKD-MBD) is a major complication of CKD. Bone turnover markers (BTMs) are important for clinicians to evaluate and manage patients with CKD-MBD. This study aimed to assess BTMs in patients with CKD and their correlation with parathyroid hormone (PTH) and other clinical characteristics of CKD.A total of 408 subjects were included in this study. The serum BTMs including N-terminal midfragment osteocalcin (N-MID OC), β-isomerized C-terminal telopeptides (β-CTX), and total procollagen type 1 amino-terminal propeptide (tPINP) were measured. Spearman correlation and multiple stepwise regression models were used to investigate the association of N-MID OC, β-CTX, and tPINP with the clinical characteristics of CKD patients.BTMs was no significant difference between non-CKD and CKD stages 1, 2, and 3. However, N-MID OC, β-CTX were significantly increased in patients with CKD stage 4 compared to non-CKD patients and patients with CKD stages 1, 2, and 3. Compared with non-dialysis dependent (NDD)-CKD stage 5, BTMs were significantly higher in dialysis patients. The estimated glomerular filtration rate was negatively associated with N-MID OC (r = -0.479, P < 0.001), β-CTX (r = -0.474, P < 0.001), and tPINP (r = -0.375, P < 0.001). Multiple analysis showed that N-MID OC (β = 0.67, P < 0.001), β-CTX (β = 0.64, P < 0.001), and tPINP (β = 0.81, P < 0.001) were independently associated with PTH. CKD patients with secondary hyperparathyroidism (SHPT) have higher β-CTX (P < 0.05), and N-MID OC (P < 0.05) than patients with non-SHPT.BTMs in advanced CKD stages were significantly higher than in the early disease stages. PTH level was independently and positively associated with the BTM levels in patients with CKD. In the advanced stage of CKD, β-CTX and N-MID OC levels were significantly higher in those with SHPT than those with non-SHPT.