CRP (C-Reactive Protein)
A marker of inflammation in the body. Used to assess infection, autoimmune conditions, and cardiovascular risk.
What is CRP?
C-reactive protein (CRP) is a substance produced by your liver in response to inflammation anywhere in the body. When tissues are injured, infected, or inflamed, your liver increases CRP production.
CRP levels rise quickly in response to acute inflammation (like an infection or injury) and fall once the inflammation resolves. This makes CRP a useful marker for detecting and monitoring inflammatory conditions.
There are two types of CRP tests:
- Standard CRP — Measures high levels (infection, acute inflammation)
- High-sensitivity CRP (hs-CRP) — Detects lower levels (chronic inflammation, cardiovascular risk)
Normal Ranges
Standard CRP
| Level | Interpretation |
|---|---|
| Below 10 mg/L | Normal |
| 10–100 mg/L | Moderate inflammation |
| Above 100 mg/L | Severe inflammation or infection |
High-Sensitivity CRP (hs-CRP)
| Level | Cardiovascular Risk |
|---|---|
| Below 1 mg/L | Low risk |
| 1–3 mg/L | Average risk |
| Above 3 mg/L | High risk |
Why It Matters
Detecting Infections
CRP rises quickly with bacterial infections, helping doctors distinguish between viral and bacterial infections and monitor treatment response.
Cardiovascular Risk
Low-grade chronic inflammation contributes to atherosclerosis (arterial plaque buildup). Elevated hs-CRP predicts heart attack and stroke risk, even in people with normal cholesterol.
Autoimmune Disease
Conditions like rheumatoid arthritis, lupus, and inflammatory bowel disease cause elevated CRP. Tracking CRP helps monitor disease activity and treatment effectiveness.
Post-Surgery Monitoring
After surgery, CRP normally rises then falls. A CRP that stays high or rises again suggests infection or complications.
What Raises CRP
Acute Causes (Standard CRP)
- Bacterial infections
- Tissue injury or trauma
- Surgery
- Burns
- Heart attack
Chronic Causes (hs-CRP)
- Obesity (fat tissue produces inflammatory substances)
- Smoking
- Poor diet (high refined carbs, low fiber)
- Lack of exercise
- Chronic stress
- Periodontal disease
- Chronic infections
How to Lower CRP
If your CRP is elevated due to lifestyle factors:
- Exercise regularly — One of the most effective interventions
- Lose excess weight — Fat tissue drives inflammation
- Eat anti-inflammatory foods — Fish, vegetables, berries, olive oil
- Limit refined carbs and sugars
- Get adequate sleep — Poor sleep raises inflammation
- Manage stress
- Don't smoke
- Treat dental problems — Gum disease raises CRP
CRP Limitations
CRP is nonspecific — it tells you inflammation exists but not where or why. A high CRP requires investigation to determine the cause.
CRP can be temporarily elevated by:
- Recent intense exercise
- Minor infections (even a cold)
- Stress
- Certain medications
This is why doctors often repeat the test or look at trends over time.
How Often to Test
- Cardiovascular risk assessment: One-time or periodic hs-CRP
- Monitoring infection: Daily or every few days during treatment
- Autoimmune conditions: Every few months to track disease activity
- Post-surgery: As directed to monitor recovery
Related Biomarkers
- ESR (another inflammation marker)
- White Blood Cells
- Lipid panel for cardiovascular risk assessment
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