FeNO Interpretation (ATS 2011)
Reads a fractional exhaled nitric oxide measurement against the age-specific cutpoints published in 2011.
Open the calculator → Runs in your browser. Data leaves only if you deliberately send a problem report from the interactive tool.
Example
- Fractional exhaled nitric oxide, parts per billion
- 30 ppb
- Age group, for the cutpoints
- Twelve years and older
Result: 30 ppb is intermediate for an adult, from 25 to 50
The tool opens with these values already filled in. Replace them with your own.
What the result means
- Twelve and older
- Below 25 ppb low, 25 to 50 intermediate, above 50 high.
- Under twelve
- Below 20 ppb low, 20 to 35 intermediate, above 35 high. The same 40 ppb is intermediate in an adult and high in a child.
- Low
- Eosinophilic airway inflammation, and a response to an inhaled corticosteroid, are both unlikely at this moment. It does not exclude asthma.
- Intermediate
- Interpret cautiously and in the clinical context. That is the guideline instruction, and it is not the same as a weak positive.
- High
- Eosinophilic airway inflammation, and a response to an inhaled corticosteroid, are both likely.
- What moves it
- Corticosteroids and active smoking lower it; atopy, allergen exposure and rhinitis raise it; a recent spirometry or a nitrate-rich meal can move it.
What you enter
- Fractional exhaled nitric oxide, parts per billion
- Age group, for the cutpoints
- On an inhaled or oral corticosteroid (lowers the number)
- Currently smoking (lowers the number)
- Atopy, allergen exposure, or rhinitis (raises the number)
- Spirometry performed shortly before (can move the number)
How this is calculated
Dweik RA, Boggs PB, Erzurum SC, et al. An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FENO) for clinical applications. Am J Respir Crit Care Med. 2011;184(5):602-615. Read the source ↗
A reference and educational tool. Not medical, legal, or financial advice, and not a substitute for clinician judgment.