ALP Predicts Mortality in Peritoneal Dialysis Patients With CKD-MBD

Elevated serum alkaline phosphatase (ALP) levels are associated with increased risks of early death in peritoneal dialysis (PD) patients with chronic kidney disease-mineral and bone disorder (CKD-MBD), according to a new Taiwanese study.

The findings, based on Asian patients, generally confirm results from an earlier study by Connie M. Rhee, MD, of the University of California-Irvine in Orange County, California, and colleagues involving white, black, and Hispanic patients (Perit Dial Int Nov-Dec 2014 34;7732-748). 

Using the nationwide Taiwan Renal Registry Data System 2005-2012 including 12,116 long-term PD patients, Yen-Chung Lin, MD, Mai-Szu Wu, MD, of Taipei Medical University Hospital, and colleagues compared the relationships between individual CKD-MBD biomarkers and all-cause mortality. During 8 years of follow-up, 3036 (25%) patients died. According to Cox regression models using time-dependent covariates, serum calcium levels of 9.5 mg/dL and above were associated with worse survival. Serum phosphorus exhibited a U-shaped relationship with mortality at levels of 6.5 mg/dL and above and below 3.5 mg/dL, possibly reflecting malnutrition. Unlike previous studies, parathyroid hormone (PTH) did not show an association with death from any cause.

Investigators observed the strongest relationship with mortality at ALP levels of 100 IU/L and above. “Our findings suggested that the detrimental effect of ALP on survival was more consistent, while serum calcium, phosphorus and PTH may have a less prominent effect on mortality,” Dr Lin, Dr Wu, and colleagues wrote in Scientific Reports. “This study provided additional information for manipulating CKD-MBD biomarkers in PD patients.”

Elevated ALP levels have been linked to cardiac failure and renal osteodystrophy, in addition to mortality. Some have suggested that CKD-MBD differs in patients undergoing PD versus hemodialysis. Although current Kidney Disease Improving Global Outcomes (KDIGO) guidelines do not offer separate advice, future research may lead to the creation of a specific practice guideline for this population, according to the researchers.

References

1. Liu CT, Lin YC, Lin YC, Kao CC, Chen HH, Hsu CC, and Wu MS. Roles of Serum Calcium, Phosphorus, PTH and ALP on Mortality in Peritoneal Dialysis Patients: A Nationwide, Population-based Longitudinal Study Using TWRDS 2005–2012. Scientific Reports doi: 10.1038/s41598-017-00080-4

2. Rhee CM, Molnar MZ, Lau WL, Ravel V, Kovesdy CP, Mehrotra R, and Kalantar-Zadeh K. Comparative Mortality-Predictability Using Alkaline Phosphatase and Parathyroid Hormone in Patients on Peritoneal Dialysis and Hemodialysis. Perit Dial Int November-December 2014 vol. 34 no. 7732-748.