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.
A C-reactive protein (CRP) test is done
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
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?).
The health professional taking a sample
of your blood will:
The 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
There is very little chance of a problem from
having a blood sample taken from a vein.
A C-reactive protein (CRP) test is a
blood test that measures the amount of a
protein called C-reactive protein in your
The 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.
Less than 1.0
milligram per deciliter (mg/dL) or less than 10
milligrams per liter (mg/L)
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.
High-sensitivity C-reactive protein (hs-CRP) measures very low
amounts of CRP in the blood. This test may help find your risk of heart problems, especially when it is considered along with other risk factors such as cholesterol, age, blood pressure, and smoking. It may be done to
find out if you have an increased chance of having a sudden heart problem, such
heart attack. But the connection between high CRP
levels and heart disease risk is not understood very well.
Less than 0.1
mg/dL or less than 1 mg/L
Less than 1.0 mg/L
1.0 to 3.0 mg/L
More than 3.0 mg/L
You may not be able to have the
test or the results may not be helpful if:
C-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.
Visit the American Heart Association (AHA) website for information on
physical activity, diet, and various heart-related conditions. You can search for information on heart disease and stroke, share information with friends and family, and use tools to help you make heart-healthy goals and plans. Contact the AHA to find your
nearest local or state AHA group. The AHA provides brochures and information
about support groups and community programs, including Mended Hearts, a
nationwide organization whose members visit people with heart problems and
provide information and support.
The U.S. National Heart, Lung, and Blood Institute
(NHLBI) information center offers information and publications about preventing
CitationsFischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.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.Other Works ConsultedBuckley 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.Greenland P, et al. (2010). 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults. Journal of the American College of Cardiology, 56(25): e50–e103.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.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.
March 6, 2012
Rakesh K. Pai, MD, FACC - Cardiology, Electrophysiology & George Philippides, MD - Cardiology
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