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

Aims . To establish Fe NO 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 Fe NO 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 Fe NO . Results . 257 adults (145 males) were retained. The proposed reference equation to predict Fe NO value is lnFe NO (ppb) = 3.47−0.56× height (m). After the predicted Fe NO 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 Fe NO (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 Fe NO 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 Fe NO higher than 26.00 ppb. Conclusion . The present Fe NO norms enrich the global repository of Fe NO norms that the clinician can use to choose the most appropriate norms.