C-reactive protein (CRP) is a crucial acute-phase protein produced by the liver in response to inflammation, infection, or tissue damage. The protein consists of five identical subunits arranged in a pentameric structure, with each subunit containing 206 amino acids.

Key Functions:

• Pathogen recognition and binding
• Opsonization to enhance phagocytosis
• Complement system activation
• Inflammation modulation

Production and Regulation:

• Triggered by pro-inflammatory cytokines, especially IL-6
• Gene located on chromosome 1 (1q23.2)
• Rapid production within hours of inflammatory stimulus
• Half-life of 18-24 hours in bloodstream

Clinical Significance:

• Normal levels: below 0.3 mg/dL
• Used as diagnostic marker for various conditions:
  • Bacterial, viral, and fungal infections
  • Autoimmune diseases (Rheumatoid Arthritis, Lupus)
  • Inflammatory Bowel Disease
  • Cardiovascular disease risk assessment
  • Cancer monitoring

Testing:

• High-sensitivity CRP (hs-CRP) testing can detect levels as low as 0.1 mg/L
• Regular monitoring helps assess:
  • Disease progression
  • Treatment effectiveness
  • Inflammation resolution

Multiple factors can influence CRP levels, including age, gender, obesity, medications, and underlying health conditions. While CRP is a valuable diagnostic tool, results should be interpreted alongside other clinical findings for accurate assessment.