C-Reactive Protein (CRP) Blood Test

By Paula Dranov

A C-reactive protein (CRP) blood test measures CRP, a substance produced in the liver in response to inflammation in the body. The inflammation may be caused by an injury or an infection (including colds and flu) and chronic conditions such as diabetes, high blood pressure, or long-standing but untreated infections such as gum disease or helicobacter pylori, the bacteria that cause ulcers. Some doctors now believe that inflammation may be even more important than your LDL (“bad” cholesterol) level in predicting heart disease.

Who Needs It
The AHA recommends a CRP test only when a doctor is not sure whether to treat a patient at intermediate risk of heart disease. This is because a patient at low risk doesn’t need treatment and a patient at high risk needs treatment, regardless of CRP levels. But some doctors recommend having a CRP test whenever you have your cholesterol checked.
           
“A high CRP level predicts high risk, even if your cholesterol is low,” says Paul Ridker, M.D., director of the Center for Cardiovascular Disease Prevention at Brigham and Women’s Hospital in Boston. “We need to identify these individuals and motivate them to live healthier lives—stop smoking, start to exercise, and lose weight, all of which lower CRP levels and cardiovascular risk.”

How It’s Done
Your blood is drawn and sent to a lab for analysis.

What You’ll Learn
This test alerts your doctor to the presence of inflammation. When inflammation is present anywhere in the body, the immune system increases production of infection-fighting white blood cells. These cells can infiltrate plaque deposits in coronary arteries and destabilize them so that they rupture, causing particles that can block an artery, thus causing a heart attack. Testing for CRP gives you an idea of whether the internal scenario set off by inflammation could be affecting your coronary arteries. The importance of CRP to heart disease risk was established in an eight-year study led by Ridker, involving 27,939 women. Of those women who eventually developed heart disease, three-fourths had LDL cholesterol below levels regarded as dangerous. Ominously, however, most of this group also had high CRP levels. Ridker estimates 25 percent of the U.S. population is in the same boat.

Cost
$10–$120, depending on where you have it done. If your doctor orders the test, it should be covered by health insurance.