About C-reactive protein (CRP)

About C-reactive protein (CRP)

CRP aids clinical management of patients with infections or inflammatory conditions

C-reactive protein (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/l1 but the concentration increases fast during bacterial infection, being able to go up to hundreds of mg/l. 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. CRP production is proportional to the intensity of infection and inflammation. Therefore, it is useful in the evaluation of disease severity. In bacterial infections, CRP may increase relatively high, above 100 mg/l. Viral and self-limiting bacterial infections cause only a minor elevation or not elevation at all. In inflammatory conditions, CRP levels may increase to moderate level, usually being between 10-40 mg/l. When the patient starts responding to treatment, the immune system overcomes the pathogen itself, or the inflammatory stimulus starts settling, CRP levels decrease rapidly back to normal with a half-life of 19h1,2.

Accurate and precise CRP point of care testing is helpful in the clinical management of patients with infection and in optimizing antibiotic prescribing. The short analytical time and a small sample volume of CRP point of care tests offer a substantial benefit compared to the laboratory CRP test. When used together with the clinical examination of a patient, QuikRead go CRP tests are excellent tools in the following situations:

  • differentiation of bacterial and viral infections
  • decreasing diagnostic uncertainty and guiding appropriate antibiotic prescribing in acute infections4,5
  • evaluation, monitoring, and prediction of the infection course, inflammation and treatment response6-8
  • ruling out severe bacterial infection9

References

  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. 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.
  6. 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.
  7. 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.
  8. 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.
  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.