C-reactive protein in the blood

, medical expert
Last reviewed: 20.11.2021

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The reference values (norm) of concentration of C-reactive protein (CRP) in blood serum - less than 5 mg / l.

C-reactive protein (CRP) is a protein consisting of 5 identical, non-covalently linked ring subunits. C-reactive protein is detected in the blood serum for various inflammatory and necrotic processes and is an indicator of the acute phase of their course. Its name was obtained because of its ability to precipitate the C-polysaccharide of the cell wall of pneumococcus. Synthesis of C-reactive protein as an acute phase protein occurs in the liver under the influence of IL-6 and other cytokines.

C-reactive protein enhances the mobility of leukocytes. By binding to T-lymphocytes, it affects their functional activity by initiating precipitation, agglutination, phagocytosis, and complement binding. In the presence of calcium, the C-reactive protein binds ligands in polysaccharides of microorganisms and causes their elimination.

The increase in the concentration of C-reactive protein in the blood begins within the first 4 hours from the moment of tissue damage, reaches a maximum after 24-72 hours, and decreases during convalescence. Increasing the concentration of C-reactive protein is the earliest sign of infection, and effective therapy is manifested by its decrease. C-reactive protein reflects the intensity of the inflammatory process, and monitoring it is important for monitoring these diseases. The content of C-reactive protein during inflammatory process can be increased 20 times or more. The concentration of C-reactive protein in the serum above 80-100 mg / l indicates a bacterial infection or systemic vasculitis. With an active rheumatic process, an increase in C-reactive protein is found in most patients. In parallel with a decrease in the activity of the rheumatic process, the content of the C-reactive protein also decreases. A positive reaction in the inactive phase may be due to focal infection (chronic tonsillitis).

Rheumatoid arthritis is also accompanied by an increase in C-reactive protein (a marker of the activity of the process), but its determination can not help in the differential diagnosis between rheumatoid arthritis and rheumatic polyarthritis. The concentration of C-reactive protein is directly related to the activity of ankylosing spondylitis. In the case of lupus erythematosus (especially in the absence of serosite), the concentration of C-reactive protein is usually not increased.

With myocardial infarction, CRB rises after 18-36 h after the onset of the disease, decreases by the 18-20th day and comes to normal by the 30-40th day. High levels of C-reactive protein in myocardial infarction (as well as in acute cerebrovascular accidents) are prognostically unfavorable signs. With angina pectoris, it remains within normal limits. C-reactive protein should be considered as an indicator of active atheromatosis and thrombotic complications in patients with unstable angina.

With edematous pancreatitis, the concentration of C-reactive protein is usually within normal limits, but it rises significantly in all forms of pancreatic necrosis. It has been established that C-reactive protein values above 150 mg / l indicate severe (pancreatic necrosis) or complicated acute pancreatitis. The study of C-reactive protein is important for determining the prognosis of acute pancreatitis. The predictive value of the positive and negative results of the C-reactive protein test for determining the unfavorable prognosis of acute pancreatitis at a separation point of more than 100 mg / l is 73%.

After surgery, the concentration of C-reactive protein increases in the early postoperative period, but begins to decline rapidly in the absence of infectious complications.

Synthesis of the C-reactive protein is enhanced in tumors of various localizations. Increase in the concentration of C-reactive protein in the blood is noted for lung cancer, prostate, stomach, ovaries and other tumors. Despite its nonspecificity, CRB, together with other cancer markers, can serve as a test for evaluating tumor progression and relapse.

There is a strong correlation between the degree of increase in C-reactive protein and ESR, however the C-reactive protein appears and disappears earlier than the ESR changes.

An increase in the concentration of C-reactive protein is characteristic of rheumatism, acute bacterial, fungal, parasitic and viral infections, endocarditis, rheumatoid arthritis, tuberculosis, peritonitis, myocardial infarction, conditions after heavy operations, malignant tumors with metastases, multiple myeloma.

The level of C-reactive protein does not increase significantly with viral and spirochete infections. Therefore, in the absence of trauma, very high values of C-reactive protein in most cases indicate the presence of a bacterial infection.

When interpreting the results of determining the concentration of C-reactive protein, it should be taken into account that an increase in the level of C-reactive protein to 10-30 mg / l is characteristic for viral infections, metastases of malignant tumors, slow chronic and a number of rheumatic diseases. Bacterial infections, exacerbation of certain rheumatic diseases (for example, rheumatoid arthritis) and tissue damage (surgery, myocardial infarction) are accompanied by an increase in the concentration of C-reactive protein to 40-100 mg / l (sometimes up to 200 mg / l), and severe generalized infections , burns, sepsis - up to 300 mg / l and more.

Determining the level of C-reactive protein in the blood serum can serve as one of the criteria for establishing indications and stopping antibiotic treatment. The level of C-reactive protein below 10 mg / l indicates no infection and there is no need for antibiotic treatment.

trusted-source[1], [2], [3], [4], [5], [6]

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