Serum Alkaline Phosphatase Levels and Mortality of Chronic Hemodialysis Patients

Objective: Alkaline phosphatase (ALP) is considered a biomarker of high bone turnover in hemodialysis (HD) patients with secondary hyperparathyroidism. This study was conducted to determine whether high serum ALP levels are associated with increased all-cause mortality of HD patients. Patients and Methods: This was a retrospective cohort study conducted at a single center. The subjects were 195 patients on chronic HD therapy who were followed up for a 5 years, and relationships between their baseline data and outcomes were assessed statistically. The serum ALP level was used as the predictor, and the primary end point was all-cause mortality. Results: Based on the median serum ALP of 236 IU/L, the subjects were divided into a low-ALP group (<236 IU/l) and a high-ALP group (≥236 IU/l). The high-ALP group was older and had a longer dialysis vintage, lower serum phosphorus concentrations, and higher serum parathyroid hormone levels, and they also had lower serum albumin levels and higher C-reactive protein values. In a multivariate Cox model in which the baseline serum ALP levels were used adjusted for age, gender, HD vintage, comorbidity, bone metabolism parameters, and serum liver enzyme levels, each doubling of the serum ALP level was associated with a significant increase in the hazard of all-cause mortality (hazard ratio 10.70, 95% CI 1.53 - 74.24). Conclusion: High baseline serum ALP levels are associated with increased mortality of HD patients, independent of bone metabolism parameters and serum liver enzyme levels. ALP is a potential target for the treatment of HD patients.