Why it's done

Your doctor might order a CRP test to check for inflammation, which can indicate infection or a chronic inflammatory disease, such as rheumatoid arthritis or lupus, as well as risk of heart disease.

CRP tests for heart disease

It's thought that a high level of hs-CRP in your blood is associated with an increased risk of heart attacks. A CRP test doesn't indicate the cause of inflammation, though, so it's possible that a high hs-CRP level could mean there's inflammation caused by something besides your heart.

The American Heart Association doesn't recommend an hs-CRP test for everyone. Rather, the test is most useful for people who have a 5 to 10 percent chance of having a heart attack within the next 10 years. This intermediate risk level is determined by the global risk assessment, which is based on lifestyle choices, family history and current health status.

The test also helps determine the risk of a second heart attack, as people with a high level of hs-CRP who had a heart attack are more likely to have another event than those with a normal level.

People who have a low risk of having a heart attack are less likely to benefit from having an hs-CRP test. People who have a known high risk of having a heart attack should seek treatment and preventive measures regardless of how high their hs-CRP level is.

Nov. 21, 2017
References
  1. Goff DC Jr., et al. 2013 ACC/AHA guideline for assessment of cardiovascular risk: A report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. Circulation. 2014;129:S49.
  2. Filippo C, et al. C-reactive protein in cardiovascular disease. https://www.uptodate.com/contents/search. Accessed Oct. 16, 2017.
  3. Morrow DA. Screening for cardiovascular disease with C-reactive protein. https://www.uptodate.com/contents/search. Accessed Oct. 16, 2017.
  4. WHO guidelines on drawing blood: Best practices in phlebotomy. World Health Organization. http://www.who.int/infection-prevention/publications/drawing_blood_best/en/. Accessed Oct. 16, 2017.
  5. Fischbach FT, et al. Immunodiagnostic studies. In: A Manual of Laboratory and Diagnostic Tests. 9th ed. Philadelphia, Pa.: Lippincott Williams & Wilkins; 2014.
  6. C-reactive protein, high sensitivity, serum. Mayo Medical Laboratories. https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/82047. Accessed Nov. 16, 2017.