C Reactive Protein (CRP)

Last updated 30.12.13

   

Definition

-  Serum blood test to aid in recognition of inflammation

 

Features

-  Part of acute phase response to acute or chronic inflammation

- Activates classical complement pathway in immune response

- Opsonises ligands for phagocytosis

- Plasma protein produced by hepatocytes

-  Typically requested with FBE

-  More specific for inflammation than ESR

- Name derived from fact it reacts with C-polysacharide of Strep pneumoniae

- Secreted within 6hrs of acute inflammation

- Peaks at around 50hrs

- Levels fall as rapidly as 5-7hrs

- Results can vary between laboratories: series CRPs should be done through same lab

 

Procedure

-  Venepuncture: light green or orange tube

 

Indication

-  Screening for infection

-  Higher levels tend to indicate bacterial rather than viral infection

-  Monitoring Inflammatory diseases: RA, AS, Vasculitis, IBD

- Coronary artery disease risk

 

Results

-  Normal: <1mg/L (<10)

-  Elevation: 1-10 mg/L

-  Cardiovascular risk

-  2-3 = average risk

- >3 = high risk

-  Elevation: >10 mg/L

-  Inflammation

-  Trauma: burns, fracture

- Necrosis: AMI, acute pancreatitis

- Cancer: lymphomea, sarcoma

- Infection: pyelonephritis, PID, meningitis, endocarditis..

- Inflammatory diseases

-  ARF, CRF

Pregnancy, elderly, Obesity: mild elevation only

-  Decreased

-  Liver impairment

 

 

References

 

Australian Prescriber: C-reactive protein 2007

Mayoclinic CRP Test & Caridovascular Risk 2013