C-Reactive Protein (CRP)
C-Reactive Protein (CRP)Skip to the navigationTest Overview A
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. High levels
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 DoneA C-reactive protein (CRP) test is done
to: - 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.
How To PrepareThere 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 DoneThe 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
alcohol.
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
blood.
- Remove the band from your arm when enough blood is
collected.
- 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
bandage.
How It FeelsThe blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
pinch. RisksThere is very little chance of a problem from
having a blood sample taken from a vein. - You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
minutes.
- In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.
Results A C-reactive protein (CRP) test is a
blood test that measures the amount of a
protein called C-reactive protein in your
blood. NormalThe normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab. Results are usually available within 24 hours. Any condition that results in sudden or severe
inflammation may increase your CRP levels. Some medicines may
decrease your CRP levels. Many conditions can change CRP
levels. Your doctor will talk with you about any abnormal results that may be
related to your symptoms and past health. What Affects the TestYou may not be able to have the
test, or the results may not be helpful, if: What To Think AboutC-reactive protein can be found with this test within a few hours of an inflammation response. So a higher-than-normal CRP level shows a current inflammation. The CRP level drops back to normal when the inflammation goes away. Other Places To Get HelpOrganizationsAmerican Heart Association www.heart.org National Heart, Lung, and Blood Institute (U.S.) www.nhlbi.nih.gov ReferencesCitations- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
Other Works Consulted- Buckley DI, et al. (2009). C-reactive protein as a risk factor for coronary heart disease: A systematic review and meta-analysis for the U.S. Preventive Services Task Force. Annals of Internal Medicine, 151(7): 483-495.
- Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Goff DC Jr, et al. (2013). 2013 ACC/AHA guideline on the assessment of cardiovascular risk: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation, published online November 12, 2013. DOI: 10.1161/01.cir.0000437741.48606.98. Accessed November 22, 2013.
- Pagana KD, Pagana TJ (2010). Mosby's Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
- Pearson TA, et al. (2003). Markers of inflammation and cardiovascular disease: American Heart Association and the Centers for Disease Control and Prevention scientific statement. Circulation, 107(3): 499-511.
- Stone NJ, et al. (2013). 2013 ACC/AHA guideline on the treatment of blood cholesterol to reduce atherosclerotic cardiovascular risk in adults: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation, published online November 12, 2013. DOI: 10.1161/01.cir.0000437738.63853.7a. Accessed November 18, 2013.
- U.S. Preventive Services Task Force (2009). Using nontraditional risk factors in coronary heart disease risk assessment. Available online: http://www.uspreventiveservicestaskforce.org/uspstf/uspscoronaryhd.htm.
CreditsByHealthwise Staff
Primary Medical ReviewerRakesh K. Pai, MD, FACC - Cardiology, Electrophysiology
E. Gregory Thompson, MD - Internal Medicine
Martin J. Gabica, MD - Family Medicine
Specialist Medical ReviewerGeorge Philippides, MD - Cardiology
Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology Current as ofSeptember 21, 2016 Current as of:
September 21, 2016 Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins. Last modified on: 8 September 2017
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