High phosphorus tied to early artery plaques

In healthy young adults, blood levels of phosphorus that fall within the high-normal range may be a risk factor for plaques or "atherosclerosis" in the coronary arteries that feed the heart, findings in the Journal of the American Society of Nephrology suggest. Coronary atherosclerosis is a major risk factor for heart attacks.

Levels of phosphorus correlate with the presence of atherosclerosis in animal studies and in humans with advanced kidney disease, noted Dr. Robert N. Foley, of the US Renal Data System, Minneapolis, Minnesota, and colleagues. "But whether this relationship exists among individuals with normal kidney function is unknown."

Phosphorus is a mineral that makes up 1 percent of a person's total body weight and is present in every cell of the body, especially the bones and teeth. The main function of phosphorus is in the formation of bones and teeth.

It also assists in maintaining kidney function, regular heartbeat and nerve conduction, and muscle contraction, among other functions.

In this study, Foley's group examined phosphorus levels in relation to the development of coronary atherosclerosis in 3,015 subjects enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study. Nearly all of the subjects had normal kidney function.

The investigators measured phosphorus when the study began and used CT scans to indirectly assess the presence of atherosclerosis 15 years later.

Overall, 3.2 percent of the participants had minimal atherosclerosis, 4.8 percent had mild atherosclerosis, 1.1 percent had moderate atherosclerosis, and 0.5 percent had severe atherosclerosis.

As phosphorus levels increased, so did the likelihood of having more and more severe atherosclerosis, the report indicates.

They note that phosphorus levels correlated with other factors, such as lower body weight, which is thought to reduce the risk of heart disease, as well as other factors, such as high triglyceride levels, which are considered detrimental.

Further research is needed to better understand these associations, the researcher conclude.

SOURCE: Journal of the American Society of Nephrology, February 2009.