Fractional exhaled nitric oxide (FeNO) is a biomarker for eosinophilic inflammation used for diagnosis and monitoring of asthma.
High FeNO indicates significant airway eosinophilia and steroid responsive airway inflammation.
According to NICE asthma guidelines updated in 2021, measurement of FeNO is recommended first followed by spirometry and brochodilator reversibility test.
FeNO can be measured with a handheld device as described in photo.
According to NICE guidelines, FeNO value above 40ppb or more is considered as positive result.
This is NICE guideline for interpreting test results for asthma in adult.
