Phosphorus as a Risk Factor for Cardiovascular Disease
Saturday, July 28, 2007
Data from the Offspring Cohort of the Framingham Study recently revealed an association between higher levels of serum phosphorus and increased cardiovascular disease (CVD) risk (Arch Intern Med 2007;167:879-885). With a sample size of 3,368 and a mean follow-up time of 16 years, investigators used statistical methods to relate serum phosphorus levels to the occurrence of a first CVD event. The data was adjusted for traditional CVD risk factors as well as standard risk factors that influence phosphorus levels including GFR, hemoglobin, albumin, proteinuria and CRP. Patients were divided into quartiles according to their phosphorus levels.
First Quartile: 1.6-2.8 mg/dL
Second Quartile: 2.9-3.1 mg/dL
Third Quartile: 3.2-3.4 mg/dL
Fourth Quartile: 3.5 mg/dL or more
Analysis of the data showed that as phosphorus levels increased, there was a continuous increase in CVD risk. People falling in the 4th quartile had a 55% higher CVD risk compared to the 1st quartile. In this study, the normal range for serum phosphorus was 2.8–4.5 mg/dL, so patients in the top quartile were within the normal range. If this association is confirmed, it may be necessary to reevaluate the normal range for phosphorus.
While this study suggests an association between phosphorus levels and CVD risk, more research will be required to determine whether it truly causes CVD. Three pathogenic mechanisms have been proposed.
1. High serum phosphorus is a marker of elevated PTH, which is proinflammatory
2. High serum phosphorus directly injures endothelium and promotes calcification
3. High serum phosphorus may be a biomarker for subclinical chronic kidney disease.
The last possibility appears less likely because CVD risk was adjusted for GFR.
posted by Fred Plapp @ 2:02 PM,
