Inflammation markers: C-reactive protein (CRP)

Acute inflammation markers before an increased leukocyte count and fever

CRP is an acute phase protein involved in the elimination of necrotic cells and the body's own toxic substances from damaged tissue, and it also binds structures that are foreign to the body, such as bacteria, fungi and parasites. It activates macrophages and the complement system. CRP regularly increases when there are acute inflammations (10 to 1000 times).

Due to its high sensitivity and specificity for acute inflammation, CRP is a diagnostically useful parameter for changes in inflammatory processes. The increase occurs after the start of the acute phase response. The level of the increase reflects the activity and the extent of the inflammation process. The half-life in the plasma is 24 hours (faster drop during recovery).

An increased serum CRP level is an important indicator for:

  • Diagnostics and monitoring of acute inflammations
  • Monitoring of patients at risk of infection
  • Differential diagnosis (DD) for Crohn’s disease / ulcerative colitis
  • Autoimmune or immunocomplex diseases
  • Tissue necrosis and malignant tumours

It is NOT possible to make a distinction between a bacterial and viral infection with certainty. Normal CRP concentrations do not exclude the possibility of mild localised inflammation or the presence of a few chronic diseases.

The peak of the increase is typically around 48 to 72 hours after the onset of inflammation. The serum half-life is approx. 24 hours. In individual cases, the time-delayed increase of CRP may cause a diagnostic gap between the initial clinical symptoms and a measurable CRP increase. In infants and children, CRP increases are considerably lower than in adults. It is faster to recognise the success of treatment by the drop in the CRP level.

Reference range
Standard range: < 5 mg/l

Test material

0.5 ml of serum

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