FENO measurement provides an easy-to-use and non-invasive tool for monitoring adherence to steroid treatment. [Beck-Ripp 2002]  

Read more under study highlights.

High FENO levels in patients on maintenance doses of inhaled corticosteroids means either they are not taking their medication as prescribed or that they are on too low a dose.

Continued high FENO levels, despite appropriate corticosteroid treatment, are most likely due to non-compliance but could also be due to:

• Poor inhalation technique

• Chronic exposure to allergens

True steroid resistance is very rare. [Stirling 1998, Payne 2001]