By now, most of us are well-versed in the rules for keeping heart disease at
bay: eat healthily, exercise, don't smoke or gain too much weight, and keep
blood pressure and cholesterol levels under control. And familiarity with terms
like HDL and LDL cholesterol is so common as to make for standard cocktail
But there's a lesser-known, relatively new player in heart-disease risk
assessment called CRP, or C-reactive protein. A study in the January 2004 issue
of The New England Journal of Medicine suggested that elevated levels
of CRP could provide doctors with information that could ultimately prevent
thousands of deaths from heart disease. But many reports have said that knowing
CRP levels provides no clinical benefit whatsoever, making the whole subject a
source of controversy.
Atherosclerosis is the process of narrowing and hardening of the arteries due to plaque buildup in the inner lining of arteries. It's the key cause of heart attacks and strokes and the No. 1 killer in the U.S.
When it comes to developing health risks from atherosclerosis, some people are at higher risk than others. But because atherosclerosis is silent until it's advanced, estimating one's health risk takes some educated guesswork.
How can you determine your risk? The risk factors are easy...
The blood test for CRP indicates inflammation, which studies have shown to
be critical in the development of atherosclerosis, or plaque build-up in the
blood vessel walls.
According to the American Heart Association and the CDC, a CRP level of less
than 1 mg per liter indicates a low risk of cardiovascular disease; 1-3 mg/L
indicates moderate risk, and greater than 3 mg/L equals high risk.
But while the test itself is simple, its implications can be confusing.
"I don't think anybody disputes that inflammation plays an important
role in artherosclerosis and its complications," says P.K. Shah, MD,
director of cardiology at Cedars-Sinai Medical Center. "But the incremental
value of CRP as a risk factor above all the conventional risk factors is
relatively small. This is the biggest bugaboo about CRP -- we don't know what
to do with the information."
One problem with the CRP test is that it's not specific, so levels can be
elevated due to other sources of inflammation besides artherosclerosis, such as
gum disease or a viral infection. (For this reason, if you do want to be tested
for CRP, doctors recommend waiting if you have an acute infection.)
Another issue is what exactly a patient should do if he is found to have a
high CRP level. Lowering CRP levels doesn't necessarily reduce risk of heart
CRP Test Not Recommended for Everyone
If you've got other risk factors for heart disease, you're most likely
already taking a cholesterol-lowering drug and aspirin therapy, and are on
lifestyle-changing programs such as routine exercise and weight loss to prevent
"Knowing your CRP level in this case wouldn't change a doctor's
recommendations," Robert Ostfeld, MD, MS, tells WebMD. Ostfeld is a
cardiologist at Montefiore Medical Center in Brooklyn, N.Y. Statin drugs as
well as standard lifestyle changes used to lower cholesterol have been shown to
lower CRP levels as well, but it's not clear that having a high CRP level yet
having other factors that only place you at a "low to moderate" risk
for future heart disease warrants treatment with a statin. An ongoing study
known as the JUPITER trial is trying to address this very issue.