July 31, 2008

Bone Disease Test Shows Death Risk for Dialysis Patients

THURSDAY, July 31 (HealthDay News) -- High levels of alkaline phosphatase -- a routinely measured marker of bone disease -- may signal an increased risk of death among patients receiving dialysis for chronic kidney disease, say U.S. researchers.

The study analyzed data on almost 74,000 hemodialysis patients during a three-year period. It found that patients with alkaline phosphatase levels above the upper limit of normal (>120 IU/L) had a 25 percent higher death rate. This association was significant across various subgroups of patients.

The study also found that patients whose alkaline phosphatase level increased during the first six months of the study were at higher risk over the subsequent two-and-one-half years.

The findings were expected to be published in the November issue of the Journal of the American Society of Nephrology.

"This large epidemiological study shows, for the first time, a consistent and robust association between a high blood level of alkaline phosphatase and cardiovascular death in thousands of dialysis patients across the United States," researcher Dr. Kamyar Kalantar-Zadeh, of the University of California, Los Angeles, said in an American Society of Nephrology news release.

"If the association between alkaline phosphatase and mortality has a causal link, treatment strategies that reduce alkaline phosphatase levels may improve survival in patients with CKD [chronic kidney disease] and probably in many other patients with chronic diseases and active bone disorders," Kalantar-Zadeh said.

Alkaline phosphatase levels are routinely measured in dialysis patients to monitor for metabolic bone disease, a common complication of CKD. However, current guidelines don't include specific recommendations or targets for alkaline phosphatase levels in patients.

"In dialysis patients, increased levels of alkaline phosphatase in the blood indicate a so-called high-turnover bone disease, which can happen due to hormonal imbalance in CKD," said Kalantar-Zadeh, who added that previous studies have identified a possible link between bone disease and cardiovascular health in CKD patients.

"Alkaline phosphatase has recently been shown to be associated with increased vascular calcification in experimental studies. Our study shows the clinical manifestation of this association in real-world patients," he said.

More information

The American Academy of Family Physicians has more about chronic kidney disease.

-- Robert Preidt
SOURCE: American Society of Nephrology, news release, July 30, 2008
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