C-Reactive Protein (CRP)

C-Reactive Protein (CRP) is an acute-phase protein produced by the liver in response to inflammation, infection, or tissue injury. It is a key biomarker used in diagnosing and monitoring inflammatory conditions.

Clinical Significance of CRP:

1. General Inflammation Marker:

   • CRP levels rise rapidly (within hours) in response to inflammation.

   • It is non-specific, meaning it does not indicate the exact cause but signals the presence of inflammation.

2. Cardiovascular Risk Assessment (hs-CRP):

   • High-Sensitivity CRP (hs-CRP) is a specialized test used to assess heart disease risk.

   • Elevated hs-CRP levels indicate chronic low-grade inflammation, which is linked to atherosclerosis and heart disease.

3. Infections and Autoimmune Diseases:

   • CRP is often elevated in bacterial infections, rheumatoid arthritis (RA), lupus, and other inflammatory diseases.

   • It helps monitor disease activity and treatment response in chronic inflammatory conditions.

Reference Ranges:

• Standard CRP Test:

  • Normal: <10 mg/L

  • Mild elevation: 10–40 mg/L (viral infections, mild inflammation)

  • Moderate elevation: 40–200 mg/L (bacterial infections, autoimmune diseases)

  • Severe elevation: >200 mg/L (severe infections, sepsis)

• High-Sensitivity CRP (hs-CRP) Test (Cardiovascular Risk):

  • Low risk: <1 mg/L

  • Moderate risk: 1–3 mg/L

  • High risk: >3 mg/L

CRP vs. ESR (Erythrocyte Sedimentation Rate):

• CRP rises and falls quickly, making it more useful for detecting acute inflammation.

• ESR changes more slowly and is influenced by factors like anemia.

• Often, both tests are used together for a more complete assessment.