Elevated Phosphate Levels a Danger for Kidney Patients

After three years, those with highest levels had highest mortality rates

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FRIDAY, Jan. 21, 2005 (HealthDayNews) -- Elevated phosphate levels may indicate an increased risk of death for people with chronic kidney disease.

That finding appears in a study in the February issue of the Journal of the American Society of Nephrology.

Researchers at the University of Washington in Seattle studied nearly 3,500 people with chronic kidney disease. At the start of the study, all of the patients had recently been checked for blood phosphate levels. Phosphate levels tended to be higher for patients with lower levels of kidney function.

Many of the patients, average age 71, had other health problems such as diabetes or heart disease.

After three years, 56 percent of the patients with the highest phosphate levels were still alive, compared with 67 percent of those in the middle levels and 72 percent of those with the lowest phosphate levels.

The study found that, above 3.5 milligrams of phosphate per deciliter of blood, the overall risk of death increased by 23 percent for every additional milligram increase in phosphate level and the risk of heart attack increased by 35 percent for each milligram increase.

It was already known that high phosphate levels are a risk factor for death for people with kidney failure who require dialysis. In these patients, high phosphate levels result in calcium deposits in large blood vessels, increasing the risk of cardiovascular disease.

This new study is one of the first to focus on phosphate as a risk factor for death among people with chronic kidney disease, a much larger group of patients. More research is needed to determine whether high phosphate levels in these patients are merely a warning sign or actually cause health problems such as heart disease, the researchers said.

More information

The U.S. National Institute of Diabetes and Digestive and Kidney Diseases has more about kidney disease.

SOURCE: Journal of the American Society of Nephrology, news release, Jan. 13, 2005


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