CRP Tests: No News We Can Use?
Study Questions Routine CRP Test for Heart-Disease Risk
Oct. 10, 2005 - You probably don't need a CRP test to know your risk of a heart attack, a new study suggests.
This doesn't mean it's good to have a lot of CRP -- C-reactive protein -- in your blood. It is not, except when your body is recovering from infection or injury.
But "traditional" risk factors tell most of us when it's time to do more for our hearts, find Michael Miller, MD, director of preventive cardiology at the University of Maryland School of Medicine, and colleagues.
"We can explain the overwhelming majority of coronary heart disease. It is pretty much under our noses," Miller tells WebMD. "We don't need to look for new avenues."
Traditional Risks Tell (Nearly) All
Only last January, a New York Times editorial warned that high CRP levels mean high heart risk -- even for people whose low cholesterol levels make them feel safe.
many of us like that? Miller's team tried to find out. Using data from 15,341 men and women enrolled in the National Health and Nutrition Examination Survey (NHANES III), they looked for people with high CRP levels.
They did, indeed, find people whose CRP levels suggested high risk of heart disease. But the vast majority of these people also had other, "traditional" risk factors. Those risk factors:
- High blood pressure
- High levels of bad LDL cholesterol
- High blood-sugar levels, or diabetes
- High blood-fat (triglyceride) levels
- Low levels of good HDL cholesterol
Only 4.4% of men and 10.3% of women had high CRP levels without having at least one of these traditional risks. Although male gender is more often associated with heart disease, women were more likely to have high CRP values.
"If all other risk factors are normal, and you exercise moderately, your risk of having high CRP is one in 2000," Miller says. "A person who is a little overweight, with blood fats and cholesterol a little elevated, maybe with a little bit of high blood pressure -- we didn't used to think that having several of these little risk factors were a big deal. But it is. These little risk factors add up in a way that is worse for you than one big risk factor."
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.