Higher Mortality Linked to Elevated Alkaline Phosphatase in CKD
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- Elevated serum alkaline phosphatase (ALP) levels are associated with increased mortality in patients with nondialysis CKD.
- Previous studies have shown that elevated ALP is associated with higher mortality in dialysis patients.
- The researchers concluded that ALP may be a surrogate marker of CKD-related mineral and bone disorders.
Elevated serum alkaline phosphatase (ALP) levels—which reflect increased bone turnover in CKD—are associated with increased mortality in patients with nondialysis CKD, researchers have concluded.
Previous studies have shown that elevated ALP is associated with higher mortality in dialysis patients.
Csaba P. Kovesdy, MD, Chief of Nephrology at Salem VA Medical Center in Salem, Va., and collaborators examined 1,158 male U.S. veterans with CKD. Subjects had a mean age of 68 years, and 24% were black.
Their mean estimated glomerular filtration rate (eGFR) was 37 mL/min/1.73 m2 and their mean serum ALP level was 91 U/L. During a median follow-up of 3.5 years, 651 patients died (a mortality of 128 per 1,000 patient-years).
Elevated baseline, time-varying, and time-averaged ALP were associated with higher mortality regardless of the level of adjustment. A 50 U/L higher time-averaged ALP was associated with a significant 17% increased mortality risk after adjusting for multiple variables, with the risk rising linearly along with ALP level. The risk similarly increased at a 75 U/L higher baseline and time-varying ALP levels, and above 75 U/L, the risk increased linearly with rising ALP levels.
The researchers concluded that ALP may be a surrogate marker of CKD-related mineral and bone disorders, but it may also be directly involved in cardiovascular calcification via degradation of pyrophosphate.