C-reactive protein

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C-reactive protein
C-reactive protein
CRP according to PDB  1B09

Existing structural data : 1b09 , 1crv , 1gnh , 1lj7

Properties of human protein
Mass / length primary structure 25 kilodaltons / 224 amino acids (Isoform1)

10 kilodaltons / 91 amino acids (isoform 2)

Secondary to quaternary structure Homopentamer
Cofactor Ca 2+
Isoforms 2
Identifier
Gene names CRP  ; MGC149895; MGC88244; PTX1
External IDs
Occurrence
Homology family CRP
Parent taxon Euteleostomi
Orthologue
human House mouse
Entrez 1401 12944
Ensemble ENSG00000132693 ENSMUSG00000037942
UniProt P02741 P14847
Refseq (mRNA) NM_000567 NM_007768
Refseq (protein) NP_000558 NP_031794
Gene locus Chr 1: 159.71 - 159.71 Mb Chr 1: 172.7 - 172.83 Mb
PubMed search 1401 12944

As C-reactive protein ( CRP ) is a protein body called, which belongs to the family of pentraxins counts. CRP is made in the liver and released into the blood . Together with ceruloplasmin , fibrinogen , haptoglobin , ferritin and others, CRP belongs to the acute phase proteins . These are proteins in the blood whose blood concentrations increase in the course of inflammatory (infectious and non-infectious) diseases. The strongest stimulus of the acute phase reaction is bacterial infections .

The CRP is used as a non-specific inflammatory parameter, among other things, to assess the severity of inflammatory diseases . Basically, the plasma CRP concentration follows the disease activity with a delay of 12 to 24 hours.

CRP is part of the immune system . It is an opsonin that can activate the complement system. The expression of CRP in the liver is most strongly stimulated by interleukin 6 (IL-6).

In 2003, CRP blood plasma levels were recommended by the US CDC as an additional marker for cardiovascular disease in otherwise healthy patients. A direct association with atherosclerosis could not be shown. A connection does not apply during inflammatory diseases, which can cause much higher CRP values.

Discovery and naming

CRP was first described in 1930 by William S. Tillett and Thomas Francis junior as a substance in the serum of patients with acute inflammation that reacts with the C - polysaccharide ( teichonic acid- containing C-substance) of pneumococci and causes precipitation together with calcium ions .

Mechanism of action

CRP binds to phosphocholine , which is found on the surface of dead or dying cells (and some types of bacteria). The bound CRP activates the complement system , binds to phagocytes and thus sets humoral and cellular effector mechanisms of the innate immune system in motion. This innate defense mechanism is considerably faster than the response of the adaptive immune system .

Reference range

CRP is also found in very low concentrations in the blood of healthy people. Values ​​of up to approx. 5 mg / l are considered normal in adults; As is usual with medical reference values, the normal value fluctuates due to influences such as patient population, analysis method and devices, which is why in principle each laboratory specifies its own limit values.

Indication for determination

  1. CRP is meanwhile the most important unspecific acute inflammatory parameter, even before the increase in the white blood cell count and fever, for example if appendicitis , cholecystitis , respiratory tract infections , diverticulitis or urinary tract infections are suspected . However, this only ever in connection with the patient's clinical symptoms.
  2. The CRP value can already be increased in the course of an illness if there is no fever or the white blood cell count is not suspicious, but the CRP increase usually follows an unspecific increase in leukocytes.
  3. The CRP value quickly drops to normal after the inflammation disappears, unlike the previously used parameter of the sedimentation reaction .
  4. As a parameter for the activity of a disease, it serves, among other things, to differentiate between acute and chronic events: In contrast to chronic diseases, acute events cause a greater increase in CRP, which usually corresponds to the extent of the inflammation.
  5. To search for rheumatic inflammatory diseases (taking into account other parameters, e.g. the rheumatoid factor )
  6. To record complicating infections, be it postoperatively, in exacerbations in the context of chronic diseases or an amniotic fluid infection with premature rupture of the bladder .
  7. To distinguish between viral and bacterial infections - is not possible by determining the CRP alone
  8. For early confirmation of successful antibacterial or anti-inflammatory therapy, as the decrease in CRP concentration often precedes clinical symptoms. The increase or decrease in the inflammatory reaction is indicated by the increase or decrease in CRP with a delay of about 24 hours.

In recent years, highly sensitive examinations for slightly increased CRP values ​​have been used to identify unstable phases in the context of arteriosclerosis .

Postoperative course

After trauma and operations , the CRP value rises physiologically to reach the highest value on the second to third day and then decrease if the course is free of complications. Normal values ​​are then reached after two to three weeks. The maximum value (" peak ") after two to three days is higher, the more severe the trauma or the intervention. For example, maximum values ​​of 136 to 154 mg / l on average are given after surgical treatment of thigh fractures, and 34 to 39 mg / l for uncomplicated ankle fractures . Open bone fractures lead to slightly higher maximum values. Even after abdominal interventions (abdominal interventions), the physiological CRP course follows the same pattern if there are no complications, with mean maximum values ​​of 140 to 159 mg / l given. With postoperative complications , especially wound infections , the CRP value can increase or remain high beyond the third day, but this has a low specificity . In contrast, a low or falling CRP value has a high negative predictive value and can rule out a wound infection with a high degree of probability.

Determination methods and serum values

The determination of the CRP in medical analysis can be done in different ways.

  • Visual latex agglutination test (qualitative)
  • Fast immunodiffusion (semi-quantitative)
  • ELISA (quantitative)
  • Highly sensitive CRP assay (for hs-CRP , English high-sensitive CRP , an inflammation-promoting acute phase protein with a normal value of less than 1 µg / l), this can result in low values ​​of CRP in serum (limit range: 0.04 mg / l) deliver in less than 30 minutes using laser nephelometry .

A "normal" or "only slightly increased" CRP includes a serious illness, e.g. B. a bacterial infection by Clostridium difficile is not excluded.

There is no significant association between smoking and CRP.

See also

Individual evidence

  1. ^ TA Pearson, GA Mensah u. a .: Markers of inflammation and cardiovascular disease: application to clinical and public health practice: A statement for healthcare professionals from the Centers for Disease Control and Prevention and the American Heart Association. In: Circulation. Volume 107, Number 3, January 2003, pp. 499-511, ISSN  1524-4539 . PMID 12551878 .
  2. ^ Tillett WS, Francis Jr T: Serological reactions in pneumonia with a nonprotein somatic fraction of pneumococcus . In: J Exp Med . 52, 1930, pp. 561-585. doi : 10.1084 / jem.52.4.561 .
  3. ↑ Hoffmann JA et al .: hylogenetic perspectives in innate immunity . In: Science . 284, 1999, pp. 1313-1318. doi : 10.1126 / science.284.5418.1313 .
  4. ↑ J. Kruidener, SA Dingemans, S. van Dieren, VM de Jong, JC Goslings, T. Schepers: C-reactive protein kinetics and its predictive value in orthopaedic (trauma) surgery: A systemic review Acta Orthopædica Belgica 2019, volume 84 , Issue 4, pages 397-406
  5. ↑ Richard Daikeler, idols Use, Sylke Waibel: diabetes. Evidence-based diagnosis and therapy. 10th edition. Kitteltaschenbuch, Sinsheim 2015, ISBN 978-3-00-050903-2 , p. 18 f.
  6. ↑ PC Konturek: Successful therapy of clostridium difficile infection with fecal microbiota transplantation. (pdf, 2.9 MB) In: Journal of Physiology and Pharmacology 2016, 67, 6. pp. 859–866 , accessed on March 4, 2017 (English).
  7. ^ S. Tonstad, JL Cowan: C-reactive protein as a predictor of disease in smokers . In: International Journal of Clinical Practice . PMC 2780563 (free full text).

Web links

  • CRP on jameda.de