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High-Sensitivity C-Reactive Protein 

  • Author: Sridevi Devaraj, PhD, DABCC, FACB; Chief Editor: Thomas M Wheeler, MD  more...
 
Updated: Sep 15, 2015
 

Reference Range

The reference range for C-reactive protein and high-sensitivity C-reactive protein are as follows:

  • CRP: 0-10mg/dL
  • hs-CRP: < 3 mg/L
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Interpretation

Relative risk of future cardiovascular events based on hs-CRP testing is estimated as follows:[1]

  • Low risk: CRP < 1.0 mg/L
  • Intermediate risk: CRP 1.0-3.0 mg/L
  • High risk: CRP > 3.0 mg/L

Acute inflammation is a CRP greater than 10.0 mg/L.

Relative risk in the high-risk group is estimated to be twice that in the low-risk group.

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Collection and Panels

Specifics for collection and panels are as follows:

  • Specimen type: Blood serum
  • Container: Vacutainer, red top (preferred; see image below) or red/black top
    Red-top vacutainer tube. Red-top vacutainer tube.
  • Collection method: Venipuncture
  • Specimen volume: 0.5 mL

Other instructions are as follows:

  • Collect fasting specimen if lipid profile tested concurrently.
  • Use the lower of 2 readings obtained at least 2 weeks apart to estimate stable CRP value.
  • Avoid testing individuals who are metabolically unstable; have had a recent illness, tissue injury, or infection; or have other any general inflammation, acute or chronic.

Related tests are as follows:

  • Lipid profile
  • Lipoprotein-associated phospholipidase A 2 (Lp-PLA 2)
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Background

Description

CRP is an acute-phase reactant synthesized by the liver in response to cytokines released by damaged tissue. Production is controlled by interluekin-6, an inflammatory cytokine. CRP is commonly measured to screen for inflammation or infection. Also, CRP is produced by cells in the vascular wall such as endothelial cells, smooth muscle cells, and also by adipose tissue.

Chronic inflammation is pivotal in heart disease; studies have shown that high levels of CRP, measured by high-sensitivity CRP (hs-CRP), can be a marker of atherosclerosis. hs-CRP is an important predictor for cardiovascular events including myocardial infarction, cerebrovascular events, peripheral vascular disease, and sudden cardiac death in individuals without a history of heart disease. In patients with acute coronary disease, CRP level predicts mortality and cardiac complications. High CRP levels portend a worse prognosis in patients with acute coronary syndromes. hs-CRP is also a marker of metabolic syndrome.[2]

Traditional assays for CRP are insufficiently sensitive for measuring the lower serum values associated with atherosclerotic disease. The newer hs-CRP assays are capable of measuring serum CRP to below 0.6 mg/dL.

High-sensitivity CRP testing has been shown to add to the predictive value of total cholesterol, low-density lipoprotein (LDL), and high-density lipoprotein (HDL), as well as the Framingham 10-year risk score.

Indications/Applications

Indications for hs-CRP testing include the following:

  • For follow-up and assessment of the risk of myocardial infarction in patients with acute coronary syndromes [3, 4, 5, 6]
  • Assessing the risk of cardiovascular disease or ischemic events in asymptomatic individuals to determine strategy for prevention of cardiovascular events

More specific recommendations from the American College of Cardiology Foundation and the American Heart Association on the use of hs-CRP testing in the assessment of cardiovascular risk in asymptomatic adults include the following:[7]

  • hs-CRP testing may be useful in selecting patients for statin therapy in men 50 years and older or women 60 years and older with LDL less than 130 mg/dL who are not on lipid-lowering, hormone replacement, or immunosuppressant therapy, who are without clinical CHD, diabetes, chronic kidney disease, severe inflammatory conditions, or contraindications to statins.
  • hs-CRP testing may be reasonable for cardiovascular risk assessment in asymptomatic men 50 years and older or women 60 years and older at intermediate risk (eg, based on Framingham Risk Score).
  • hs-CRP testing has not been shown to be beneficial for cardiovascular risk assessment and is not recommended in asymptomatic high-risk individuals.

Considerations

Oral contraceptives may increase serum CRP.

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Contributor Information and Disclosures
Author

Sridevi Devaraj, PhD, DABCC, FACB Medical Director of Clinical Chemistry and POCT, Texas Children's Hospital; Professor of Pathology and Immunology, Baylor College of Medicine; Associate Director of Translation, Texas Children's Microbiome Center

Disclosure: Nothing to disclose.

Chief Editor

Thomas M Wheeler, MD Chairman, Department of Pathology and Immunology, WL Moody, Jr, Professor of Pathology, Professor of Urology, Baylor College of Medicine

Thomas M Wheeler, MD is a member of the following medical societies: Alpha Omega Alpha, American Association for Cancer Research, American Medical Association, American Society for Clinical Pathology, American Society of Cytopathology, American Thyroid Association, American Urological Association, College of American Pathologists, United States and Canadian Academy of Pathology, International Society of Urological Pathology, Harris County Medical Society

Disclosure: Received stock from PathXL for medical advisory board. for: PathXL, Inc.

Acknowledgements

Judy Lin, MD

Disclosure: Nothing to disclose.

References
  1. Pearson TA, Mensah GA, Alexander RW, et al. Markers of inflammation and cardiovascular disease: application to clinical and public health practice: A statement for healthcare professionals from the Centers for Disease Control and Prevention and the American Heart Association. Circulation. 2003 Jan 28. 107(3):499-511. [Medline].

  2. Casas JP, Shah T, Hingorani AD, Danesh J, Pepys MB. C-reactive protein and coronary heart disease: a critical review. J Intern Med. 2008 Oct. 264(4):295-314. [Medline].

  3. Parrinello CM, Lutsey PL, Ballantyne CM, Folsom AR, Pankow JS, Selvin E. Six-year change in high-sensitivity C-reactive protein and risk of diabetes, cardiovascular disease, and mortality. Am Heart J. 2015 Aug. 170 (2):380-389.e4. [Medline].

  4. Shi MY, Xue FH, Teng SC, Jiang L, Zhu J, Yin F, et al. Effect of Atorvastatin on Serum Levels of Total Cholesterol and High-Sensitivity C-Reactive Protein in High-Risk Patients with Atrial Fibrillation in Asia. Clin Ther. 2015 Jul 6. [Medline].

  5. Ribeiro DR, Ramos AM, Vieira PL, Menti E, Bordin OL Jr, Souza PA, et al. High-sensitivity C-reactive protein as a predictor of cardiovascular events after ST-elevation myocardial infarction. Arq Bras Cardiol. 2014 Jul. 103 (1):69-75. [Medline].

  6. Noren Hooten N, Ejiogu N, Zonderman AB, Evans MK. Protective Effects of BDNF against C-Reactive Protein-Induced Inflammation in Women. Mediators Inflamm. 2015. 2015:516783. [Medline].

  7. Greenland P, Alpert JS, Beller GA, et al. 2010 ACCF/AHA guideline for assessment of cardiovascular risk in asymptomatic adults: executive summary: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2010 Dec 21. 122(25):2748-64. [Medline].

  8. Burris CA, Ashwood ER, Burns DE. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 4th ed. St Louis: Elsevier Saunders; 962-7, 1633.

  9. Devaraj S, Singh U, Jialal I. Human C-reactive protein and the metabolic syndrome. Curr Opin Lipidol. 2009 Jun. 20(3):182-9. [Medline]. [Full Text].

  10. McPherson RA, Matthew R, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia: Elsevier Saunders; 254-5.

 
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Red-top vacutainer tube.
 
 
 
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