What is this test?
Fractional Exhaled Nitric Oxide (FeNO) is a simple non-invasive breath test that measures the level of nitric oxide in exhaled air. Elevated FeNO indicates Type 2 (eosinophilic) airway inflammation.
Why is it done?
FeNO assists in: supporting the diagnosis of asthma, guiding decisions about inhaled corticosteroid treatment, monitoring response to anti-inflammatory therapy, and identifying patients likely to benefit from certain biologic treatments.
Who may benefit?
- Patients with suspected or confirmed asthma
- Assessment of airway inflammation
- Monitoring treatment response
- Selected patients with chronic cough
How is it performed?
You breathe in deeply, then exhale slowly and steadily at a controlled flow rate into the device. The test takes only a few minutes and requires no special effort.
Patient Preparation
Avoid eating, exercise and use of inhaled medications for at least 1 hour before the test. Do not smoke on the day of testing. Inform the clinic team of all current medications.
What information does it provide?
A FeNO value above 50 ppb (parts per billion) in adults is considered high and suggests significant eosinophilic airway inflammation. Values between 25-50 ppb are intermediate. Values below 25 ppb are generally considered low.
