Were you looking for the CRP test, used to evaluate general inflammation?
At a Glance
Why Get Tested?
To help assess your risk of developing cardiovascular disease
When to Get Tested?
No current consensus exists on when to get tested; hs-CRP is often ordered in conjunction with other tests that are performed to assess risk of heart disease, such as a lipid profile (cholesterol, triglycerides, HDL-C, LDL-C) when your healthcare provider would like additional information on your risk.
A blood sample drawn from a vein in your arm
Test Preparation Needed?
You may be instructed to fast for 9-12 hours before the blood sample is taken if a lipid profile also is going to be done at the same time. You should be healthy at the time of the sample collection, without any recent illnesses, infections, inflammation, or injuries.
The Test Sample
What is being tested?
C-reactive protein (CRP) is a protein that increases in the blood with inflammation and infection as well as following a heart attack, surgery, or trauma. Thus, it is one of several proteins that are often referred to as acute phase reactants. The high-sensitivity CRP test measures low levels of CRP in the blood to identify low levels of inflammation that are associated with risk of developing cardiovascular disease (CVD).
There are two different tests that measure CRP and each test measures a different range of CRP level in the blood for different purposes:
- The standard CRP test measures markedly high levels of the protein to detect diseases that cause significant inflammation. It measures CRP in the range from 10 to 1000 mg/L.
- The hs-CRP test accurately detects lower levels of the protein than the standard CRP test and is used to evaluate individuals for risk of CVD. It measures CRP in the range from 0.5 to 10 mg/L.
It is now believed that a persistent low level of inflammation plays a major role in atherosclerosis, the narrowing of blood vessels due to build-up of cholesterol and other lipids, which is often associated with CVD.
CVD causes more deaths in the U.S. each year than any other cause, according to the American Heart Association. A number of risk factors, such as family history, high cholesterol, high blood pressure, being overweight or diabetic, have been linked to the development of CVD, but a significant number of people who have few or no identified risk factors will also develop CVD. This fact has lead researchers to look for additional risk factors that might be either causing CVD or that could be used to determine lifestyle changes and/or treatments that could reduce a person's risk.
High-sensitivity CRP is one of a growing number of cardiac risk markers that are used to help determine a person's risk. Some studies have shown that measuring CRP with a highly sensitive assay can help identify the risk level for CVD in apparently healthy people. This more sensitive test can measure CRP levels that are within the higher end of the reference range. These normal but slightly high levels of CRP in otherwise healthy individuals can predict the future risk of a heart attack, stroke, sudden cardiac death, and peripheral arterial disease, even when cholesterol levels are within an acceptable range.
How is the sample collected for testing?
A blood sample is drawn by needle from a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed; however, fasting for 9-12 hours before the blood sample is taken may be required if a lipid profile (including triglycerides) is to be done at the same time. In addition, the person being tested should be healthy at the time of the sample collection, without any recent illnesses, infections, inflammation, or injuries.
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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
Sources Used in Current Review
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Delgado, J. et. al. (2014 November). Cardiovascular Disease (Non-traditional Risk Markers) - Risk Markers - CVD (Non-traditional). ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/CVDRiskMarkerNontrad.html?client_ID=LTD through http://www.arupconsult.com. Accessed February 2015.
Yousuf, O. et. al. (2013). High-Sensitivity C-Reactive Protein and Cardiovascular Disease, A Resolute Belief or an Elusive Link? Medscape Multispecialty from J Am Coll Cardiol. 2013;62(5):397-408 [On-line information]. Available online at http://www.medscape.com/viewarticle/808448 through http://www.medscape.com. Accessed February 2015.
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Whelton, S. et. al. (2013). Elevated High-sensitivity C-reactive Protein as a Risk Marker of the Attenuated Relationship Between Serum Cholesterol and Cardiovascular Events at Older Age, The ARIC Study. Medscape Multispecialty from Am J Epidemiol. 2013;178(7):1076-1084 [On-line information]. Available online at http://www.medscape.com/viewarticle/811811 through http://www.medscape.com. Accessed February 2015.
Pagana, K. D., Pagana, T. J., and Pagana, T. N. (© 2015). Mosby's Diagnostic & Laboratory Test Reference 12th Edition: Mosby, Inc., Saint Louis, MO. Pp 306-307.
(March 1, 2012) Assessing Cardiovascular Risk: Guideline Synthesis. Agency for Healthcare Research and Quality (AHRQ). Available online at http://www.medscape.com/viewarticle/759314_4 through http://www.medscape.com. Accessed March 4, 2015.
Sources Used in Previous Reviews
American College of Cardiology clinical trials pages. Available online at http://www.acc.org/education/online/trials/acc2001/prince.htm through http://www.acc.org.
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Ridker PM, Hennekens CH, Buring JE, and Rifai N. C-reactive protein and other markers of inflammation in the prediction of cardiovascular disease in women. NEJM 2000; 342:836-843. (March 23, 2000).
ARUP Lab fact sheet. Available online at http://www.aruplab.com/guides/clt through http://www.aruplab.com.
American Heart Association Journal Report 01/28/2003. AHA/CDC panel issues recommendations on CRP testing. Available online at http://www.americanheart.org/presenter.jhtml?identifier=3007984 through http://www.americanheart.org.
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