Higher Blood Phosphorus Levels May Predict Increased Calcium Levels in Coronary Arteries

Laurie Barclay, MD

November 26, 2008

November 26, 2008 — Young healthy adults with higher levels of phosphorus in the blood are more likely to have increased levels of calcium in the coronary arteries, according to the results of a study reported in the November 5 issue of the Journal of the American Society of Nephrology.

“Phosphorus levels correlate with atherosclerosis in both animal models and humans with advanced chronic kidney disease, but whether this relationship exists among individuals with normal kidney function is unknown,” write Robert N. Foley, from the Cardiovascular Special Studies Center, United States Renal Data System, and the University of Minnesota in Minneapolis, and colleagues. “This study aimed to determine whether an association exists between phosphorus levels and coronary artery calcium levels in a community-based cohort of 3015 healthy young adults in the prospective Coronary Artery Risk Development in Young Adults (CARDIA) study.”

Participants underwent baseline measurement of phosphorus levels and computed tomography 15 years later to evaluate the presence of coronary artery calcium. At study entry, mean age was 25.2 years; mean phosphorus level was 3.6 mg/dL, and mean calcium level was 9.5 mg/dL. Estimated glomerular filtration rate was less than 60 mL/min per 1.73 m2 in only 0.2% of participants.

In unadjusted models, phosphorus levels were associated with coronary artery calcium, and in multivariate models, phosphorus levels were significantly associated with the category of coronary artery calcium level.

Study limitations include nonexperimental design preventing determination of whether the association between phosphorus levels and coronary calcification is a true phenomenon or of the magnitude of residual confounding; inability to determine the relative contributions of genetic and environmental factors to the associations; lack of data on parathyroid hormone and vitamin D levels; limited sample size; and somewhat self-selected study sample.

“Higher serum phosphorus levels, even within the normal range, may be a risk factor for coronary artery atherosclerosis in healthy young adults,” the study authors write. “Quite apart from the underlying determinants, the associations seen in this study suggest that high phosphorus levels might help to identify young adults for whom modifiable risk factors might be screened and managed more aggressively.”

The National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, funded this study. Three of the authors report various financial arrangements with Amgen and/or Genzyme.

J Am Soc Nephrol. Published online November 5, 2008.

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