The relationship between coronary artery calcification and bone metabolic markers in maintenance hemodialysis patients

Background To study the influencing factors for coronary artery calcification (CAC) in maintenance hemodialysis (MHD) patients and the relationship between CAC and bone metabolism markers and to attempt to find a reliable marker linking vascular calcification and bone metabolism in MHD patients. Methods A total of 123 patients were enrolled. CAC was assessed by multislice spiral computed tomography (MSCT), and the CAC score (CACS) was evaluated using the Agaston method. Routine laboratory parameters, including triglycerides (TG), total cholesterol (TC), glucose (Glu), calcium (Ca), phosphorus (P), magnesium (Mg), etc., were measured. Serum markers of bone metabolism, such as alkaline phosphatase(ALP), calcitonin (CT), 25-hydroxy vitamin D [25-(OH)D], intact parathyroid hormone (iPTH), total type I procollagen amino-terminal peptide (tPINP), N-terminal mid-fragment of osteocalcin (N-MID OC), and beta-type I collagen crosslinked carboxyl-terminal peptide (beta- CTX), were also measured. Results Among 123 MHD patients, 37 patients (30.08%) did not have CAC, and 86 patients (69.92%) had CAC, including 41 patients (47.67%) with mild calcification and 45 patients (52.33%) with moderate to severe calcification. Age, Body Mass Index(BMI), the prevalence of hypertension and diabetes mellitus, TC, Glu, P, and CaxP in the calcification group were higher than those in the noncalcification group, whereas Mg, iPTH, tPINP, N-MID OC, and beta-CTX were lower than those in the noncalcified group (P < 0.05). Compared with the mild calcification group (0<CACS<400), P and CaxP levels were higher in the moderate to severe calcification group (CACS = 400), and ALP, iPTH, N-MID OC, tPINP, and beta-CTX concentrations were lower (P < 0.05). Correlation analysis showed that the CACS was positively correlated with TC, LDL-C, P, and CaxP (P < 0.05) and negatively correlated with N-MID OC and beta-CTX (P < 0.05). There was no significant correlation between the CACS and other parameters (P > 0.05). A logistic regression model was used to evaluate the influencing factors for CAC. The results showed that age, BMI, TC, Glu, P, and CaxP were risk factors for CAC and its severity in MHD patients, whereas diabetes mellitus, Mg, and N-MID OC were protective factors for CAC in MHD patients. In addition, N-MID OC was a protective factor for the severity of CAC. After adjusting for the corresponding confounding factors, the results of the risk factors were consistent, and N-MID OC was still an independent protective factor for CAC and its severity.