C-reactive protein (CRP)
Why this test?
To diagnose various inflammatory diseases caused by infection or autoimmune processes, and to evaluate the effectiveness of their treatment.
For differential diagnosis of bacterial and viral infection (with viral infections, the level of CRP is slightly increased).
To determine the activity of the inflammatory, autoimmune process.
For the diagnosis of postoperative infectious complications.
To diagnose hidden infections.
To assess the need for antibacterial therapy and its duration.
To give a forecast of the course and possible fatal outcome in some acute conditions (for example, pancreatic necrosis).
To assess tumor progress and disease recurrence (when determined jointly with other tumor markers). For differential diagnosis of inflammatory bowel diseases: Crohn's disease (high CRP) and nonspecific ulcerative colitis (low CRP).For differential diagnosis of rheumatoid arthritis (high CRP) and uncomplicated lupus (low CRP).
To monitor the activity of chronic diseases.
In what cases is it prescribed?
In case of suspicion of an infectious disease in case of patients with fever, in case of neutropenia, suspicion of meningitis in children, sepsis in newborns.
When examining patients with autoimmune pathology (arthritis, vasculitis).
When carrying out antibacterial therapy.
In the postoperative period (for early detection of infectious complications and assessment of the effectiveness of antibacterial therapy) - if complications develop, the level of CRP will remain elevated or increase for 4-5 days after surgery.
In the treatment of chronic inflammatory diseases.When transplanting organs (kidneys, hearts).
During preventive examination and observation of patients with chronic diseases, neoplasms.
C-reactive protein is a glycoprotein that is produced by the liver and belongs to the proteins of the acute phase of inflammation. Under the influence of anti-inflammatory cytokines (interleukin-1, tumor necrosis factor - alpha and especially interleukin-6), its synthesis increases after 6 hours, and the concentration in the blood increases 10-100 times within 24-48 hours after the onset of inflammation. The highest levels of CRP (more than 100 mg/l) are observed with bacterial infection. With a viral infection, the level of CRP, as a rule, does not exceed 20 mg / l.
The concentration of CRP also increases with tissue necrosis (including myocardial infarction, tumor necrosis). CRP participates in the activation of complement (a group of proteins that are part of immunity), monocytes, stimulation of the expression of adhesion molecules ICAM-1, VCAM-1, E-selectin on the surface of the endothelium (they ensure the interaction of cells), binding and modification of low-density lipids density (LDL), that is, promotes the development of atherosclerosis. A progressive increase in CRP is associated with the activity of the inflammatory process and the degree of tissue damage. Moreover, CRP is a more sensitive indicator of active inflammation than the erythrocyte sedimentation rate (ESR), but it rises and disappears earlier than the ESR changes.
An increase in CRP may precede the onset of fever, pain, and other signs of illness. Some experts determine the duration of antibacterial therapy depending on the timing of CRP reduction. In the uncomplicated postoperative period, CRP reaches maximum values on the third day and decreases to a normal level within a week. Preservation of high values of CRP and lack of its gradual decrease indicates the attachment of infection. Separate determination of CRP does not allow clarifying the diagnosis and nature of the disease, but with high sensitivity it makes it possible to establish the fact of active inflammation or tissue damage. The results of the analysis should be interpreted taking into account the indicators of other laboratory tests, the clinical picture of the disease and the conclusions of instrumental studies.