ABSTRACT
OBJECTIVE: This study aimed to compare two sampling methods for nasal nitric oxide in healthy individuals and allergic rhinitis patients, and to examine the within-subject reliability of nasal nitric oxide measurement. METHODS: The study included 23 allergic rhinitis patients without concomitant asthma and 10 healthy individuals. For all participants, nitric oxide levels were measured non-invasively from the lungs through the mouth (i.e. the oral fractional exhaled nitric oxide) and the nose. Nasal nitric oxide was measured by two different methods: (1) nasal aspiration via one nostril during breath holding and (2) single-breath quiet exhalation against resistance through a tight facemask (i.e. the nasal fractional exhaled nitric oxide). RESULTS: Compared with healthy participants, allergic rhinitis patients had significantly higher average oral and nasal nitric oxide levels. All methods of nitric oxide measurement had excellent reliability. CONCLUSION: Nasal nitric oxide measurement is a useful and reliable clinical tool for diagnosing allergic rhinitis in patients without asthma in an out-patient setting.
