Exhaled Nitric Oxide in a Taiwanese Population: Age and Lung Function as Predicting Factors

Background/PurposeThe fractional concentration of exhaled nitric oxide (FENO) has been reported to be elevated in asthma and many other lung diseases. The present study investigated reference values and determinants of FENO in a Taiwanese non-smoking, healthy adult population.MethodsWe used a chemiluminescence analyzer according to American Thoracic Society/European Respiratory Society recommendations to measure FENO values in 356 adults who received a health check-up and a detailed respiratory questionnaire at Taichung Veterans General Hospital, Taiwan. Among the volunteers, 249 fulfilled our definition of healthy adults: no history of smoking or physician-diagnosed asthma; no recent upper airway infection; no chronic respiratory symptoms; and no allergic rhinitis and urticaria.ResultsAmong the 249 non-smoking and non-asthmatic adults, the mean (5th to 95th percentile reference range) FENO was 27.9 (12.5–58.0) parts per billion. In multivariate regression analyses, age and lung function (forced vital capacity or forced expiratory volume in 1 second) were associated positively with FENO values. Sex, height, weight, and ambient NO values were not associated significantly with FENO values.ConclusionAge and lung function were predictors of FENO in this population, and these factors should be considered for clinical applications of FENO measurements.