P1400ASSOCIATION BETWEEN MEAN SERUM MAGNESIUM LEVEL DURING THE FIRST 3 YEARS OF HEMODIALYSIS AND THE RISK OF SUBSEQUENT BONE FRACTURES

Background and Aims Serum magnesium levels are an important factor associated with vital prognosis, cardiovascular disease, and vascular calcification in hemodialysis patients. Moreover, low serum magnesium levels are reportedly associated with an increased risk of hip fractures. Previously we reported that mean magnesium level during the first 3 years of hemodialysis was associated with all-cause mortality in ERA-EDTA 2018. Here, we investigated whether mean magnesium level during the first 3 years of hemodialysis can predict fracture risk. Method A retrospective cohort study was conducted in 283 patients who started hemodialysis at our hospital between March 2004 and the present and who could be followed for at least 3 years or had a fracture within 3 years. To assess the association between mean serum magnesium level during 3 years after the start of hemodialysis or until fracture and fracture risk, a multivariate analysis was performed using the Cox proportional hazard model with factors related to fractures as covariates, with all fractures such as hip fracture and spinal compression fracture as the outcome. Results The mean follow-up period was 6.1 years, and the mean age of patients was 64 years, with women accounting for 31%. Of all 283 patients, 62 developed fractures. A univariate analysis of factors associated with fractures revealed that high serum magnesium level was a significant fracture suppressor (hazard ratio [HR]: 0.31 [0.12–0.73]). Multivariate analysis conducted with significant factors in univariate analysis (mean serum albumin level, serum phosphorus level, hemoglobin level, C-reactive protein level, age, history of heart disease, history of bone fractures, and use or nonuse of phosphate binder during the 3 years) as the covariates revealed that the serum magnesium level was not significantly associated with bone fractures (HR: 0.95 [0.33–2.78]), whereas, old age, history of fractures, low albumin level, high CRP level, and nonuse of phosphate binder were significantly associated with fractures. Conclusion Serum magnesium levels during 3 years after the initiation of hemodialysis did not predict the risk of subsequent fractures, whereas a high level of inflammatory response, malnutrition, and nonuse of phosphate binder did.