Blood Phosphorus Levels Can Predict Heart Trouble

Coronary artery calcification (CAC) is detected readily by computerized tomography (CT) screening.  It’s presence indicates atherosclerosis, with the two lesions comprising ‘hardening of the arteries’.  Not surprisingly, CAC correlates with an increased risk of a heart attack.  One problem with CAC screening is that the amount of radiation from the CT screen is measurable, though it varies widely (10-fold) depending on the technique used.  Another is that it can turn up ‘incidental findings’ in the heart or lungs that are most probably not clinically relevant, but often need further investigation ‘just to make sure’. 

A solution to this problem is the recent demonstration that serum phosphate levels are linked to CAC scores.  The work is published online in the Clinical Journal of the American Society of Nephrology.   

Data came from 883 community-dwelling adults in the Spokane Heart Study.  At enrollment, CAC was present in 28% of them.  The participants were assessed every 2 years for CAC, cardiovascular risk factors, and blood studies.  After 6 years, new-onset CAC was found in 33% of the 371 subjects examined, and CAC had worsened in those who had it at baseline.  Analyses showed that CAC was more likely to progress in participants with greater baseline CAC scores, and in those with higher serum phosphorus levels, worse kidney function, and traditional cardiovascular risk factors. 

Every 1 mg/dL increase in serum phosphorus increased the likelihood of CAC increase more than 1½ times.  This magnitude was equivalent to that of traditional cardiovascular risk factors. 

This finding may lead to future attempts to reduce calcium deposition in the tissues by less phosphate in the diet or the use of phosphate-binding substances (other than calcium).  And serum phosphate determination may help replace the use of CT screening for CAC detection.