Reactivity of High-Sensitivity C-Reactive Protein
hsCRP is highly reactive, rising several hundredfold in response to acute injury, infection, or inflammatory stimuli, making it an extremely sensitive marker of inflammation. 1
Magnitude of Response to Inflammatory Stimuli
CRP demonstrates dramatic reactivity with increases of several hundredfold during acute inflammatory states, distinguishing it from baseline levels used for cardiovascular risk assessment 1
Traditional CRP cutoffs define reactivity ranges: 10-40 mg/L indicates mild inflammation, while 40-200 mg/L reflects acute inflammation and bacterial infection 1
The marker's reactivity is so pronounced that levels above 10 mg/L should prompt retesting in 2 weeks to exclude acute infections, arthritis, or other non-cardiovascular inflammatory conditions 2, 3
Clinical Implications of hsCRP Reactivity
Distinguishing Chronic from Acute Inflammation
For cardiovascular risk assessment, hsCRP measures much lower concentrations (0.3-3 mg/L range) that reflect chronic vascular inflammation, not acute inflammatory responses 1
The American College of Cardiology recognizes three cardiovascular risk categories: <1 mg/L (lower risk), 1-3 mg/L (moderate risk), and >3 mg/L (higher risk) 2
Persistently unexplained marked elevations >10 mg/L after repeated testing require evaluation for non-cardiovascular causes before attributing the elevation to atherosclerotic risk 3
Factors Modulating hsCRP Reactivity
Conditions that increase hsCRP levels include: 1, 2
- Elevated blood pressure
- Increased body mass index
- Cigarette smoking
- Metabolic syndrome and diabetes
- Low HDL cholesterol and high triglycerides
- Chronic infections (gingivitis, bronchitis)
- Chronic inflammatory conditions (rheumatoid arthritis)
Factors that decrease hsCRP levels include: 1, 2
- Moderate alcohol consumption
- Regular exercise and increased physical activity
- Weight loss
- Statin therapy
- Fibrates and niacin
Analytical Stability and Measurement Characteristics
One of hsCRP's most attractive features is its exceptional preanalytical stability in serum or plasma, remaining stable at room temperature or frozen for extremely long periods 1
Modern hsCRP assays can detect concentrations accurately and reproducibly down to 0.3 mg/L, with between-day precision ranging from 4-8% coefficient of variation 1
The high reactivity of CRP means that a single elevated measurement may reflect transient inflammation rather than chronic cardiovascular risk, which is why the American Heart Association recommends using results alongside other risk factors for clinical decision-making 2