About C-reactive protein (CRP) (2024)

What is C-reactive protein (CRP)?

C-reactive protein (CRP) is an extensively studied and widely used analyte in healthcare. CRP measurement aids in the diagnosis, evaluation, and monitoring of infection, tissue injury, inflammatory disorders, and associated diseases.CRP is an acute-phase plasma protein present in healthy individuals at low concentrations. The median CRP level of healthy people is usually < 0.8 mg/l and the reference value for CRP is < 3 mg/l1. However, each laboratory is recommended to establish the reference value for their population in the region.

Bacterial infections and inflammatory conditions stimulate the production of CRP in the liver. From the initial stimulus, CRP levels become detectable in 4-6 hours and peak in 36-48 hours2,3. In turn, when the infection or inflammation settles, CRP levels decrease rapidly back to normal with a half-life of 19h1,2.

CRP aids in the evaluation of disease severity and efficacy of antibiotic therapy

CRP production is proportional to the intensity of infection and inflammation4. Therefore, it is useful in the differentiation of mild and severe infections. If CRP level is < 10 mg/l, bacterial infection is unlikely5. In severe systemic bacterial infections, CRP may increase up to hundreds of mg/l. Viral and mild/self-limiting bacterial infections cause only a minor elevation or not elevation at all. Also, in the inflammatory diseases, CRP levels follow the severity of inflammation and may increase to moderate level, usually being between 10-40 mg/l.

CRP levels decrease rapidly as a response to treatment and infection resolution, making it a valuable tool to monitor the effectiveness of antibiotic treatment and disease progression. If CRP level does not decline within days after initiation of antibiotic therapy, it may be a sign of complicated disease or suggest ineffective antibiotic treatment6.

CRP point of care testing aids management of acute infections and guides antibiotic prescribing

Accurate, precise, and fast CRP point of care (POC) testing aids in the clinical management of patients with acute infection and optimises antibiotic prescribing. A small sample volume and immediate results due to the short analytical time offer a substantial benefit compared to a laboratory CRP test. When used together with the clinical examination of a patient, QuikRead go CRP tests are excellent tools in the following situations:

  • differentiating mild and severe infections4
  • increasing diagnostic confidence and guiding appropriate antibiotic prescribing in acute infections7,8
  • evaluation, monitoring, and prediction of the infection course, inflammation and treatment response6-9
  • ruling out severe bacterial infection10,11


  1. Shine, B et al. Solid phase radioimmunoassays for C-reactive protein. Clin. Chim. Acta 1981; 117:13–23.
  2. Vigushin DM, Pepys MB, Hawkins PN. Metabolic and scintigraphic studies of radioiodinated human C-reactive protein in health and disease. J Clin Invest 1993; 91(4): 1351-1357.
  3. Pepys MB, Hirschfield GM. C-reactive protein: a critical update. J Clin Invest 2003; 111(12): 1805-1812.
  4. Markanday A. Acute Phase Reactants in Infections: Evidence-Based Review and a Guide for Clinicians. Open Forum Infect Dis 2015; 2(3): ofv098.
  5. National Institute for Health and Care Excellence (NICE). NICE guideline - Pneumonia in adults: diagnosis and management (CG191), 2014.
  6. Bruns AH et al. Usefulness of consecutive C-reactive protein measurements in follow-up of severe community-acquired pneumonia. Eur Respir J 2008; 32(3): 726-732.
  7. Little P et al. Effects of internet-based training on antibiotic prescribing rates for acute respiratory-tract infections: a multinational, cluster, randomised, factorial, controlled trial. Lancet 2013; 382(9899): 1175-1182.
  8. Tonkin-Crane SKG et al. Clinician-targeted interventions to influence antibiotic prescribing behaviour for acute respiratory infections in primary care: an overview of systematic reviews (Review). Cohcrane Database of Systematic Reviews 2017; 7(9): CD012252.
  9. Emery P. Evidence-based review of biologic markers as indicators of disease progression and remission in rheumatoid arthritis. Rheumatol Int 2007; 27(9): 793-806.
  10. Verhagen DW et al. Prognostic value of serial C-reactive protein measurements in left-sided native valve endocarditis. Arch Intern Med 2008; 168(3): 302-307.
  11. Chalmers JD, Singanayagam A, Hill AT. C-Reactive Protein Is an Independent Predictor of Severity in Community-acquired Pneumonia. Am J Med 2008; 121(3):219-225.
    About C-reactive protein (CRP) (2024)


    What level of CRP is concerning? ›

    Results equal to or greater than 8 mg/L or 10 mg/L are considered high. Range values vary depending on the lab doing the test. A high test result is a sign of inflammation. It may be due to serious infection, injury or chronic disease.

    What is the meaning of C-reactive protein CRP? ›

    CRP is a protein that is made in your liver and released into your bloodstream. Levels of CRP start to increase very soon after any inflammation or infection affects your body. The CRP blood test can be used to find out how severe inflammation is, or whether you are responding to treatment.

    What kind of inflammation causes high CRP? ›

    A wide variety of inflammatory conditions can cause elevated CRP levels, including :
    • autoimmune conditions, including rheumatoid arthritis (RA), lupus, and certain types of inflammatory bowel disease (IBD), such as Crohn's disease and ulcerative colitis.
    • pericarditis, which is inflammation of the lining of the heart.

    What happens if the CRP level is high? ›

    High levels of CRP may mean you have a serious health condition that causes inflammation. Inflammation is your body's way of protecting your tissues and helping them heal from an injury, infection, or other disease. Inflammation can be acute (sudden) and temporary. This type of inflammation is usually helpful.

    What is a safe CRP level? ›

    Normal Range of CRP Level in the Blood

    A normal range falls between 0 to 3 milligrams per liter (mg/L) of blood. Elevated levels may signal an underlying health concern. While there is no such thing as a “low” CRP level, the normal range is generally less than 0.9 mg/dL.

    What level of CRP indicates arthritis? ›

    Normal C-reactive protein (CRP) levels
    C-reactive protein level (in milligrams per liter of blood) in adultsWhat it means
    10.0–100.0moderately elevated, which signifies infection or an inflammatory condition such as rheumatoid arthritis (RA), Crohn's disease, or lupus
    4 more rows

    What cancers can CRP detect? ›

    CRP is considered to be related to cancer progression, and increased serum levels of CRP have been detected in many carcinomas, such as colorectal (8), lung (9) and gastric cancer (10-12).

    What should I avoid if my CRP is high? ›

    Limiting or avoiding inflammatory foods like refined carbohydrates, fried foods, red meat and processed meat can help reduce CRP. Instead, focus on eating more anti-inflammatory foods like leafy greens, nuts, fatty fish and whole grains.

    What autoimmune disease causes CRP? ›

    The C-reactive protein (CRP) test is used to find inflammation in your body. Inflammation could be caused by different types of conditions, such as an infection or autoimmune disorders like rheumatoid arthritis or inflammatory bowel disease. This test measures the amount of CRP in your blood.

    How do I get my CRP levels down? ›

    There's no doubt that the very best way to lower CRP is through exercise, weight loss, and dietary control; of course, those are all proven already to lower vascular risk. There is a paper that came out in February comparing the Atkins diet, the Zone diet, the Weight Watchers diet, and the Ornish diet.

    What medication is used to treat CRP? ›

    Cyclooxygenase inhibitors (aspirin, rofecoxib, celecoxib), platelet aggregation inhibitors (clopidogrel, abciximab), lipid lowering agents (statins, ezetimibe, fenofibrate, niacin, diets), beta-adrenoreceptor antagonists and antioxidants (vitamin E), as well as angiotensin converting enzyme (ACE) inhibitors (ramipril, ...

    What happens if high CRP is left untreated? ›

    When CRP remains high, it is an indication of chronic inflammation. Elevated CRP is a risk factor for many chronic inflammation-related disorders, including cardiovascular disease, cancer, diabetes, obesity, and more.

    What is a critical level of CRP? ›

    Interpretation of CRP levels:

    More than 10.0 mg/dL: Marked elevation (Acute bacterial infections, viral infections, systemic vasculitis, major trauma). More than 50.0 mg/dL: Severe elevation (Acute bacterial infections).

    What CRP level indicates sepsis? ›

    Initial CRP levels did not differ among patients with sepsis or septic shock (median CRP level day 1 in sepsis: 150 (97–225) mg/l; septic shock: 127 (79–219) mg/l; p = 0.092). However, in the presence of septic shock, CRP was shown to increase until day 10 of ICU hospitalization (median 179 (66–225) mg/l).

    What CRP level indicates Crohn's disease? ›

    Conclusion: CRP elevation in Inflammatory Bowel Disease is associated with active disease determined endoscopically, histologically, or radiographically. In both CD and UC, a CRP > 2.0 mg/dL predicts findings of active ileal disease at ileocolonoscopy.

    What autoimmune disease causes high CRP? ›

    Your healthcare provider may also order the test if they think you have an inflammatory condition or an autoimmune disease, such as rheumatoid arthritis. CRP levels are higher in people with these conditions. This test may also be used to watch flare-ups and recovery.

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