FENO (Breath Test): A Simple Way to Measure Airway Inflammation

What Is a FENO Test?

The FENO (Fractional Exhaled Nitric Oxide) test measures nitric oxide levels in your breath. This gas is a biomarker of inflammation in the lungs. It helps doctors understand if your airways are inflamed, often due to asthma.

Why Is Nitric Oxide Important?

Nitric oxide is produced by cells lining your lungs. When your airways are inflamed, these cells produce more of it. Higher levels often point to eosinophilic inflammation, common in allergic or asthmatic conditions.

Who Needs a FENO Test?

Doctors recommend FENO testing for:

• People with suspected asthma.
• Patients with uncontrolled asthma symptoms.
• Those on inhaled corticosteroids needing dose adjustments.
• Children with breathing issues.

It’s also useful in determining if steroid treatment will work for a patient.

How Is the Test Performed?

The FENO test is non-invasive and painless. You simply exhale into a handheld device. The entire test takes less than 5 minutes. Results are available almost instantly.

You must avoid eating, drinking, or exercising 1 hour before the test. These can affect the nitric oxide levels in your breath.

What Do the Results Mean?

• Low FENO (≤25 ppb in adults, ≤20 ppb in children): Indicates little to no airway inflammation.
• Intermediate FENO (25–50 ppb): May suggest mild inflammation.
• High FENO (>50 ppb): Sign of significant eosinophilic airway inflammation.

Doctors consider your history and symptoms alongside FENO scores. It’s not a standalone diagnostic tool.

Benefits of the FENO Test

• Fast and accurate.
• No blood required.
• Helps monitor asthma treatment.
• Guides medication adjustments.
• Ideal for children and adults alike.

FENO vs. Other Asthma Tests

Spirometry tests lung function. Blood tests measure eosinophils. But FENO directly checks inflammation. It adds value where other tests might not be clear.

FENO is especially useful when symptoms don’t match spirometry results. It can clarify what’s really happening inside the lungs.

Limitations to Consider

Certain factors can affect FENO results, including:

• Smoking
• Respiratory infections
• Diet (nitrate-rich foods)
• Age and height

Always follow pre-test instructions and discuss your results with a healthcare provider.

FENO in Asthma Management

FENO testing plays a key role in personalized asthma care. It helps reduce overuse of medications. It also helps prevent undertreatment. Patients with high FENO often benefit from inhaled steroids. Those with low levels may not need them.

Doctors use FENO alongside other tools to track asthma control over time.

Conclusion: FENO Test Simplifies Asthma Care

The FENO breath test is a game-changer in respiratory care. It delivers quick insights into airway inflammation. It aids in diagnosis and helps guide effective treatment. Fast, simple, and reliable—it’s an essential tool for anyone managing asthma.