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Asthma Intake
FeNO Testing
Measurement of fractional exhaled nitric oxide to assess eosinophilic airway inflammation.
Eosinophilic inflammationuse cases
Overview
FeNO (Fractional exhaled Nitric Oxide) testing measures the amount of nitric oxide in exhaled breath, which indicates eosinophilic inflammation in the airways - a key feature of allergic asthma.
eosinophilic Inflammation
description
Type of airway inflammation driven by eosinophils (a type of white blood cell)
significance
- Common in allergic asthma
- Responds well to inhaled corticosteroids
- Can be measured and monitored with FeNO
markers
High FeNO levels indicate active eosinophilic inflammation
process
description
- Patient breathes out slowly and steadily into a device
- Device measures nitric oxide concentration
- Quick and non-invasive test
- Results available immediately
duration
Takes just a few minutes to perform
interpretation
levels
- Low (<25 ppb in adults): Minimal eosinophilic inflammation
- Intermediate (25-50 ppb): Moderate inflammation
- High (>50 ppb): Significant eosinophilic inflammation
factors
- Age (children have different normal ranges)
- Atopy (allergic tendency)
- Current medications
- Recent allergen exposure
use Cases
diagnosis
- Supporting asthma diagnosis
- Identifying eosinophilic phenotype
- Distinguishing types of airway inflammation
monitoring
- Assessing response to inhaled corticosteroids
- Monitoring inflammation control
- Guiding treatment adjustments
- Predicting exacerbation risk
treatment
- Identifying patients likely to respond to corticosteroids
- Guiding biologic therapy selection
- Monitoring biologic therapy effectiveness
benefits
- Non-invasive and quick
- Immediate results
- No medication holds required
- Useful for monitoring treatment response
limitations
- Not diagnostic alone - must be interpreted with other tests
- Can be affected by recent food intake
- Normal levels don't rule out asthma
- Results can vary with technique
preparation
- Avoid eating or drinking (except water) 1 hour before
- No specific medication holds usually needed
- Follow provider's specific instructions
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