C-Reactive Protein (CRP)
C-Reactive Protein (CRP) is an acute-phase protein produced by the liver in response to inflammation. CRP levels rise rapidly during infections, injuries, and autoimmune processes, and fall during recovery. It is a universal marker of systemic inflammation.
Disclaimer. This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider for interpretation of test results.
Normal Ranges
| Test | Value |
|---|---|
| Standard CRP (normal) | < 5 mg/L |
| hs-CRP (normal) | < 1 mg/L |
| hs-CRP (moderate cardiovascular risk) | 1–3 mg/L |
| hs-CRP (high cardiovascular risk) | > 3 mg/L |
Standard CRP vs. hs-CRP
- Standard CRP detects significant inflammation (infections, autoimmune flares, post-surgical). Range: 5–200+ mg/L.
- High-sensitivity CRP (hs-CRP) detects low-grade chronic inflammation for cardiovascular risk assessment. Range: 0–10 mg/L.
Causes of Elevated CRP
- Bacterial infections (pneumonia, pyelonephritis, sepsis) — major elevation (50–200+ mg/L)
- Viral infections — moderate elevation (10–40 mg/L)
- Autoimmune diseases (rheumatoid arthritis, lupus, Crohn's disease)
- Acute myocardial infarction
- Malignancies
- Obesity (chronic low-grade inflammation)
Related Biomarkers
- Ferritin — also an acute-phase protein, rises with inflammation
- Hemoglobin — anemia of chronic inflammation
- Glucose — chronic inflammation is linked to insulin resistance
CRP and Cardiovascular Risk
Even mildly elevated hs-CRP (1–3 mg/L) is associated with increased risk of heart attack and stroke, independent of cholesterol levels. Evaluate alongside the lipid panel for comprehensive risk assessment.
Monitoring
CRP is a convenient marker for tracking treatment effectiveness. With successful antibiotic therapy or autoimmune remission, levels drop rapidly. Health Vault automatically tracks inflammatory marker trends over time.
FAQ
Do I need to fast for CRP? Standard CRP can be tested at any time. For hs-CRP, fasting is recommended.
What should I do if CRP is elevated? The underlying cause of inflammation needs to be identified. Your doctor will order additional tests based on the clinical picture.
How often should I check hs-CRP? For cardiovascular risk assessment — every 1–2 years if you have risk factors.
Last updated: June 2026