C-reactive protein test
C-reactive protein test
C-reactive protein (CRP) is a normal protein that can be measured in the blood. It appears in higher amounts when there's swelling somewhere in your body. Your doctor may check your C-reactive protein level after surgery or treatment for infections or other medical conditions. The C-reactive protein test can also be used to check your risk of developing coronary artery disease, a condition in which the arteries of your heart are narrowed. Coronary artery disease can eventually lead to a heart attack.
Your C-reactive protein level can be checked with a simple blood test. Some researchers think that by treating people with high C-reactive protein levels, it's less likely they might have a heart attack or stroke. A C-reactive protein test is not right for everyone. It may not be helpful in determining your heart attack risk, depending on your health and lifestyle choices.
Why it's done
A C-reactive protein (CRP) test checks for swelling (inflammation). CRP is a protein that builds up in your blood only when there's inflammation somewhere in your body. Your doctor may order a CRP test to monitor these conditions:
CRP tests for heart disease
Having a CRP test to check your heart disease risk isn't a good option for everyone, however. According to the American Heart Association, a CRP test is most useful for people who have an intermediate risk (a 10 to 20 percent chance) of having a heart attack within the next 10 years. This score, called the global risk assessment, is based on lifestyle choices, family history and your current health status. People who have a low risk of having a heart attack are less likely to benefit from having a CRP test, and people who have a high risk of having a heart attack should seek treatment and preventive measures regardless of how high their CRP level is.
There's little risk in getting a CRP test. You may have some soreness or tenderness around the site where your blood is drawn. Rarely, the site where your blood is drawn may become infected. These risks aren't any different from those of other times that you have your blood drawn.
How you prepare
There are no special preparations for a CRP test. However, if your doctor is checking your CRP level to find out your heart attack risk, you may need other blood tests that would require you to fast or follow other instructions. Talk to your doctor to see if you'll need any additional blood tests that will be done at the same time as your CRP test.
Some medications — such as birth control pills; statins; nonsteroidal anti-inflammatory drugs (NSAIDs), including ibuprofen (Motrin, Advil, others); and acetaminophen (Tylenol, others) — can affect your CRP level. Tell your doctor if you take these medications regularly.
What you can expect
During the procedure
Blood is drawn from a vein, usually from your arm. Before the needle is inserted, the puncture site is cleaned with antiseptic and an elastic band is wrapped around your upper arm. This causes the veins in your arm to fill with blood.
After the needle is inserted, a small amount of blood is collected into a vial or syringe. The band is then removed to restore circulation, and blood continues to flow into the vial. Once enough blood is collected, the needle is removed and the puncture site is covered with a pressure wrap.
The entire procedure will likely last a couple of minutes. It's relatively painless.
After the procedure
It may take a few days for you to get your results back. Your doctor should explain to you what the results of your test mean.
If you're having a CRP test to help find out your heart disease risk, keep in mind that your CRP level is only one risk factor for coronary artery disease. If your result shows you have a high CRP level, it doesn't necessarily mean you're at a higher risk of developing heart disease. Talk to your doctor about your other risk factors and ways you can try to prevent coronary artery disease and a heart attack.
Your doctor will discuss what your CRP test results mean.
If you're having a CRP test to evaluate your risk of heart disease, these are the current risk levels used:
Keep in mind that these risk levels aren't a definitive measure of your risk because there's disagreement on whether a high CRP level is a true risk factor for heart disease.
A test result showing a CRP level greater than 10 mg/dL is a sign of serious inflammation or infection, and you should talk to your doctor about your test result to check for other medical problems.
It's possible your doctor will suggest more tests, such as a cholesterol test, a stress test or a coronary angiogram, to further look into your coronary artery disease risk. He or she may also recommend lifestyle changes or medications to decrease your risk of a heart attack.
Last Updated: 2009-12-16
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