C-Reactive Protein (CRP)
C-reactive protein (CRP) test is a blood test that measures the amount of a
protein called C-reactive protein in your blood.
C-reactive protein measures general levels of
inflammation in your body.
of CRP are caused by infections and many long-term diseases. But a CRP test
cannot show where the inflammation is located or what is causing it. Other
tests are needed to find the cause and location of the inflammation.
Why It Is Done
A C-reactive protein (CRP) test is done
- Check for infection after surgery. CRP levels
normally rise within 2 to 6 hours of surgery and then go down by the third day
after surgery. If CRP levels stay elevated 3 days after surgery, an infection
may be present.
- Identify and keep track of infections and diseases
that cause inflammation, such as:
- Check to see how well treatment is working, such
as treatment for cancer or for an infection. CRP levels go up quickly and then
become normal quickly if you are responding to treatment measures.
A special type of CRP test, the high-sensitivity CRP test
(hs-CRP), may be done to find out if you have an increased chance of having a
sudden heart problem, such as a
heart attack. Inflammation can damage the inner lining
of the arteries and make having a heart attack more likely. But the
connection between high CRP levels and heart attack risk is not understood very
How To Prepare
There is no special preparation for a
C-reactive protein (CRP) test. You might be asked to not eat or drink for a few hours before the test.
Tell your doctor all of the medicines you are taking because some medicines can affect the results.
Talk to your doctor about any
concerns you have regarding the need for the test, its risks, how it will be
done, or what the results will mean. To help you understand the importance
of this test, fill out the
medical test information form(What is a PDF document?).
How It Is Done
The health professional taking a sample
of your blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a