C-Reactive Protein and Erythrocyte Sedimentation Rate Testing

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Effective Date: December 5, 2018

Recommendations and Topics

Scope

This guideline applies to the clinical use of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) as investigative tests in adults aged ≥ 19 years.

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Key Recommendations

  • CRP is the preferred first test to support a diagnosis of inflammatory or infectious conditions, rather than ESR. There is no indication for ordering ESR when CRP is elevated.
  • According to the British Columbia Laboratory Services Outpatient Payment Schedule, ESR will be performed only if a written indication is provided on the requisition. If CRP and ESR are ordered together, most outpatient laboratories will only perform CRP because only CRP is payable.1
  • Clinical features that together may prompt a requisition for CRP are:
    1. unexplained symptoms or a deterioration of health status; and
    2. an inflammatory or infectious disease is suspected; and
    3. a specific diagnosis is not made effectively by other means.
  • Repeat testing for CRP depends on the clinical status of the patient. It may be used in routine monitoring of patients with inflammatory arthritis and other rheumatic conditions. For most infections, repeat CRP is not indicated and assessment should be made on clinical grounds (e.g., when following treatment of cellulitis,2 pneumonia or urinary tract infections).
  • The only indication for CRP assessment in asymptomatic individuals is in the stratification of cardiovascular risk. High sensitivity (hs) CRP is one of several tools which may be used in patients at intermediate cardiovascular risk to help decide whether a statin should be started. If hsCRP is desired, it should be specifically requested on the laboratory requisition.
  • In the appropriate clinical context, and if CRP is normal, then ESR may provide useful information when:
  1. Used in combination with other biomarkers in patients who are known to have systemic lupus erythematosus (SLE) or other rheumatic conditions and who are known not to mount a CRP response.3–5
  2. Used in combination with other clinical tests when considering the possibility of low-grade bone and joint infections (e.g., osteomyelitis6 and early prosthetic joint infections5).

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Background

CRP is produced in the liver as part of the acute phase response. It is directly measurable and responsive to changes in the inflammatory process. CRP concentration peaks rapidly, approximately 48 hours after the inflammatory stimulus.7 When the stimulus for production stops, CRP decreases quickly.7

ESR is an indirect measure of inflammation. ESR levels increase at a slow rate in response to inflammation and can take weeks to return to normal levels.5 A variety of factors influence the sedimentation rate such as physiological factors (e.g., older age, female gender and pregnancy5, 8), pathological factors (e.g., plasma immunoglobulin and fibrinogen concentrations5) and technical issues.9 Hence, CRP is the preferred test when considering investigating an inflammatory clinical state.

Compared to CRP, false negative and false positive test results can occur when measuring ESR due to the slow response rate and lack of specificity respectively.5 However, both tests have limited diagnostic ability and their appropriate uses are outlined in the Tests section below. If the clinical history and physical exam findings are suggestive of specific disease processes, other investigations are usually more appropriate.

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Tests

According to the British Columbia Laboratory Services Outpatient Payment Schedule, ESR will be performed only if a written indication is provided on the requisition. If CRP and ESR are ordered together, most outpatient laboratories will only perform CRP because only CRP is payable.1

CRP and ESR in British Columbia - MSP Cost of Tests1

Test Fee Item Cost
ESR (fee item 90515) $10.61
CRP/hsCRP (fee item 91300) $10.31

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C-Reactive Protein

CRP may be ordered:

  1. during the diagnosis of inflammatory and infectious disease;
  2. during monitoring of inflammatory and infectious disease; or
  3. to review a therapeutic approach in primary prevention of cardiovascular disease in patients assessed at intermediate risk. This is the only indication for CRP assessment in asymptomatic individuals.

All CRP assays measure the same protein though laboratories differ in their measurement methods. High sensitivity (hs) CRP is a designation given to laboratory assays that measure CRP levels below 3 mg/L. Laboratories reporting CRP values less than 3 mg/L are using an hsCRP assay. CRP and hsCRP perform equally well for the diagnosis and monitoring of infectious and other inflammatory conditions. CRP assays measuring below 3 mg/L (hsCRP) can be used to stratify patients for cardiovascular disease risk (see Table 1 below). If hsCRP is desired for cardiovascular risk stratification, hsCRP should be specified on the laboratory requisition as it may need to be forwarded to a laboratory that performs this test.

Table 1. Utility of hsCRP and CRP Assays for Cardiovascular Risk Stratification and in the Diagnosis and Monitoring of Inflammatory or Infectious Disease

Assay Cardiovascular
Risk Stratification
Inflammation/
Infection
Lower Limit of Detection
hsCRP YES YES 0.1 – 0.3 mg/L
(note: this value varies between laboratories)
CRP (non hsCRP) NO YES 3 – 5 mg/L
(note: this value varies between laboratories)

Inflammation and Infection

Within the appropriate clinical context, CRP levels above 10 mg/L can help support the diagnosis of an inflammatory or infectious process. However, CRP levels less than 10 mg/L do not rule out an inflammatory or infectious process.

Clinical features that together may prompt a requisition for CRP are:

  1. unexplained symptoms or a deterioration of health status; and
  2. an inflammatory or infectious disease is suspected; and
  3. a specific diagnosis is not made effectively by other means.

CRP may be used to monitor the activity of:

  1. rheumatic conditions such as vasculitis (e.g., temporal (giant cell) arteritis10–12 and polymyalgia rheumatica13, 14) and inflammatory arthritis (e.g., rheumatoid arthritis15, 16 and SLE3, 4);
  2. inflammatory bowel disease (e.g., ulcerative colitis and Crohn’s disease);17 or
  3. infections which require long term antibiotics and which are difficult to monitor clinically (e.g., osteomyelitis18 or prosthetic joint infections).

Repeat testing for CRP depends on the clinical status of the patient. It may be used in routine monitoring of patients with inflammatory arthritis and other rheumatic conditions. For most infections, repeat CRP is not indicated and assessment should be made on clinical grounds (e.g., when following treatment of cellulitis,2 pneumonia or urinary tract infections).

hsCRP and Cardiovascular Disease (CVD)

When a patient without clinical cardiovascular disease is found to be at intermediate risk for CVD based on their Framingham Risk Score, hsCRP is one of several tools which can be used to raise or lower their estimated cardiovascular risk (see the associated BC Guideline Cardiovascular Disease – Primary Prevention for further information on cardiovascular disease risk stratification). Patients at moderate cardiovascular risk who have an hsCRP > 2mg/L (and typically < 10 mg/L) may benefit from statin therapy.19, 20

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Erythrocyte Sedimentation Rate

CRP is the preferred first test to support a diagnosis of inflammatory or infectious conditions, rather than ESR. There is no indication for ordering ESR when CRP is elevated.

In the appropriate clinical context, and if CRP is normal, then ESR may provide useful information when:

  1. Used in combination with other biomarkers in patients who are known to have systemic lupus erythematosus (SLE) or other rheumatic conditions and who are known not to mount a CRP response.3–5
  2. Used in combination with other clinical tests when considering the possibility of low-grade bone and joint infections (e.g., osteomyelitis6 and early prosthetic joint infections5).

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Resources

Patient and Caregiver Resources

References

  1. Ministry of Health. Laboratory Services Outpatient Payment Schedule - Province of British Columbia [Internet]. [cited 2018 Jun 13]. Available from: https://www2.gov.bc.ca/gov/content/health/practitioner-professional-resources/laboratory-services-diagnostic-services/laboratory-services/information-for-laboratory-operators/laboratory-services-outpatient-payment-schedule
  2. Lazzarini L, Conti E, Tositti G, de Lalla F. Erysipelas and cellulitis: clinical and microbiological spectrum in an Italian tertiary care hospital. J Infect. 2005 Dec;51(5):383–9.
  3. Schäfer VS, Weiß K, Krause A, Schmidt WA. Does erythrocyte sedimentation rate reflect and discriminate flare from infection in systemic lupus erythematosus? Correlation with clinical and laboratory parameters of disease activity. Clin Rheumatol. 2018 Jul;37(7):1835–44.
  4. Gordon C, Amissah-Arthur M-B, Gayed M, Brown S, Bruce IN, D’Cruz D, et al. The British Society for Rheumatology guideline for the management of systemic lupus erythematosus in adults. Rheumatology. 2018 Jan 1;57(1):e1–45.
  5. Harrison M. Erythrocyte sedimentation rate and C-reactive protein. Aust Prescr. 2015 May 31;38(3):93–4.
  6. Michail M, Jude E, Liaskos C, Karamagiolis S, Makrilakis K, Dimitroulis D, et al. The performance of serum inflammatory markers for the diagnosis and follow-up of patients with osteomyelitis. Int J Low Extrem Wounds. 2013 Jun;12(2):94–9.
  7. Pepys MB, Hirschfield GM. C-reactive protein: a critical update. J Clin Invest. 2003 Jun 15;111(12):1805–12.
  8. Bray C, Bell LN, Liang H, Haykal R, Kaiksow F, Mazza JJ, et al. Erythrocyte Sedimentation Rate and C-reactive Protein Measurements and Their Relevance in Clinical Medicine. WMJ Off Publ State Med Soc Wis. 2016;115(6):317–21.
  9. Alberta Laboratory Quality Enhancement Program. Erythrocyte Sedimentation Rate (ESR) [Internet]. College of Physicians and Surgeons of Alberta. 2000 [cited 2018 Nov 1]. Available from: http://www.cpsa.ca/wp-content/uploads/2016/08/ESR-Educational-Document-.pdf
  10. Hayreh SS, Podhajsky PA, Raman R, Zimmerman B. Giant Cell Arteritis: Validity and Reliability of Various Diagnostic Criteria. Am J Ophthalmol. 1997 Mar 1;123(3):285–96.
  11. Walvick MD, Walvick MP. Giant Cell Arteritis: Laboratory Predictors of a Positive Temporal Artery Biopsy. Ophthalmology. 2011 Jun 1;118(6):1201–4.
  12. Kermani TA, Schmidt J, Crowson CS, Ytterberg SR, Hunder GG, Matteson EL, et al. Utility of Erythrocyte Sedimentation Rate and C-Reactive Protein for the Diagnosis of Giant Cell Arteritis. Semin Arthritis Rheum. 2012 Jun;41(6):866–71.
  13. Cantini F, Salvarani C, Olivieri I, Macchioni L, Ranzi A, Niccoli L, et al. Erythrocyte sedimentation rate and C-reactive protein in the evaluation of disease activity and severity in polymyalgia rheumatica: a prospective follow-up study. Semin Arthritis Rheum. 2000 Aug;30(1):17–24.
  14. Salvarani C, Cantini F, Niccoli L, Macchioni P, Consonni D, Bajocchi G, et al. Acute-phase reactants and the risk of relapse/recurrence in polymyalgia rheumatica: a prospective followup study. Arthritis Rheum. 2005 Feb 15;53(1):33–8.
  15. Crowson CS, Rahman MU, Matteson EL. Which measure of inflammation to use? A comparison of erythrocyte sedimentation rate and C-reactive protein measurements from randomized clinical trials of golimumab in rheumatoid arthritis. J Rheumatol. 2009 Aug;36(8):1606–10.
  16. NRAS - National Rheumatoid Arthritis Society [Internet]. [cited 2018 Jul 31]. Available from: https://www.nras.org.uk/laboratory-tests-used-in-the-diagnosis-andmonitoring-of-rheumatoid-arthritis
  17. Mosli MH, Zou G, Garg SK, Feagan SG, MacDonald JK, Chande N, et al. C-Reactive Protein, Fecal Calprotectin, and Stool Lactoferrin for Detection of Endoscopic Activity in Symptomatic Inflammatory Bowel Disease Patients: A Systematic Review and Meta-Analysis. Am J Gastroenterol. 2015 Jun;110(6):802–19; quiz 820.
  18. Van Asten SA, Nichols A, La Fontaine J, Bhavan K, Peters EJ, Lavery LA. The value of inflammatory markers to diagnose and monitor diabetic foot osteomyelitis. Int Wound J. 2017 Feb;14(1):40–5.
  19. Ridker PM, Danielson E, Fonseca FAH, Genest J, Gotto AM, Kastelein JJP, et al. Rosuvastatin to prevent vascular events in men and women with elevated C-reactive protein. N Engl J Med. 2008 Nov 20;359(21):2195–207.
  20. Anderson TJ, Grégoire J, Pearson GJ, Barry AR, Couture P, Dawes M, et al. 2016 Canadian Cardiovascular Society Guidelines for the Management of Dyslipidemia for the Prevention of Cardiovascular Disease in the Adult. Can J Cardiol. 2016 Nov 1;32(11):1263–82.

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Abbreviations

CRP - C-Reactive Protein
ESR - Erythrocyte Sedimentation Rate
hsCRP - High sensitivity C-Reactive Protein
SLE - Systemic lupus erythematosus

Contributors to the guideline

Contributors to guideline (PDF, 108 KB)

This guideline is based on scientific evidence current as of the effective date.

The guideline was developed by the Guidelines and Protocols Advisory Committee in collaboration with BC’s Agency for Pathology and Laboratory Medicine and adopted by the Medical Services Commission.

THE GUIDELINES AND PROTOCOLS ADVISORY COMMITTEE

The principles of the Guidelines and Protocols Advisory Committee are to:

  • encourage appropriate responses to common medical situations
  • recommend actions that are sufficient and efficient, neither excessive nor deficient
  • permit exceptions when justified by clinical circumstances

Contact Information:

Guidelines and Protocols Advisory Committee
PO Box 9642 STN PROV GOVT
Victoria BC V8W 9P1

Email: hlth.guidelines@gov.bc.ca
Website: www.BCGuidelines.ca

Disclaimer

The Clinical Practice Guidelines (the “Guidelines”) have been developed by the Guidelines and Protocols Advisory Committee on behalf of the Medical Services Commission. The Guidelines are intended to give an understanding of a clinical problem, and outline one or more preferred approaches to the investigation and management of the problem. The Guidelines are not intended as a substitute for the advice or professional judgment of a health care professional, nor are they intended to be the only approach to the management of clinical problem. We cannot respond to patients or patient advocates requesting advice on issues related to medical conditions. If you need medical advice, please contact a health care professional.

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