CRP Tests: No News We Can Use?
Study Questions Routine CRP Test for Heart-Disease Risk
Why CRP Is Important
Miller doesn't think routine screening for CRP is a good idea. But he stresses that what CRP measures is immensely important. In fact, it's the essence of heart disease.
CRP is a marker for inflammation -- the body's first line of defense against infection and injury. When fats build up in the arteries, the body fights them by mounting an immune response. It's a good idea that leads to disaster, says Russell P. Tracy, PhD, Russell P. Tracy, PhD, professor of pathology and biochemistry at the University of Vermont College of Medicine, Burlington. Tracy was part of the team that developed the first test for CRP.
"Because there is a constant infusion of fat particles into the artery wall, the inflammation never goes away," Tracy tells WebMD. "If the blood-fat concentration is high enough, this essentially swamps the system. ... So it is not the fat in the artery that is the problem, it is the immune response to that."
And CRP is, at the moment, the best way to measure this deadly immune response. But since CRP levels are linked to traditional risk factors, Tracy agrees with Miller that not everyone needs a CRP test.
"My opinion is that the public is still best served by finding risk factors a person can work on," Tracy says. "For some people, obesity might be the main risk. For others it might be a high LDL cholesterol level. While knowing CRP and cholesterol ratios might help define the risk, you will have lost the information about the source of the increased inflammation."
Not so fast, says heart disease expert Ishwarlal Jialal, MD, PhD, director of the laboratory for atherosclerosis and metabolic research at the University of California, Davis.
Jialal notes that the Miller study used a relatively insensitive CRP test. This, he says, likely missed a lot of people with dangerous CRP levels but only borderline traditional risk factors. If these people had their CRP measured by current methods, their doctors would be more likely to advise immediate action.
Moreover, Jialal says, monitoring CRP would tell doctors how well treatment -- lifestyle change and treatment with cholesterol-lowering drugs -- is working.
"If you only look at cholesterol and blood fats, you miss the additional risk that CRP portends," Jialal tells WebMD. "CRP is important. And recent studies show when you lower CRP and LDL cholesterol, you have a greater benefit than lowering LDL alone."