Fraction of Exhaled Nitric Oxide (FeNO) Norms in Healthy Tunisian Adults

AIMS To establish FeNO norms for healthy Tunisian adults aged 18-60 years and to prospectively assess their reliability. METHODS This was a cross-sectional analytical study. A convenience sample of healthy Tunisian adults was recruited. Subjects responded to a medical questionnaire, and then FeNO levels were measured by an online method (Medisoft, Sorinnes (Dinant), Belgium). Clinical, anthropometric, and plethysmographic data were collected. All analyses were performed on natural logarithm values of FeNO. RESULTS 257 adults (145 males) were retained. The proposed reference equation to predict FeNO value is lnFeNO (ppb) = 3.47-0.56× height (m). After the predicted FeNO value for a given adult was computed, the upper limit of normal could be obtained by adding 0.60 ppb. The mean ± SD (minimum-maximum) of FeNO (ppb) for the total sample was 13.54 ± 4.87 (5.00-26.00). For Tunisian and Arab adults of any age and height, any FeNO value greater than 26.00 ppb may be considered abnormal. Finally, in an additional group of adults prospectively assessed, we found no adult with a FeNO higher than 26.00 ppb. CONCLUSION The present FeNO norms enrich the global repository of FeNO norms that the clinician can use to choose the most appropriate norms.