title: Fraction of exhaled nitric oxide (FeNO ) norms in healthy North African children 5-16 years old.
abstract: OBJECTIVE
  (i) To identify factors that influence the FeNO values in healthy North African, Arab children aged 6-16 years; (ii) to test the applicability and reliability of the previously published FeNO norms; and (iii) if needed, to establish FeNO norms in this population, and to prospectively assess its reliability.
  
  
  METHODS
  This was a cross-sectional analytical study. A convenience sample of healthy Tunisian children, aged 6-16 years was recruited. First subjects have responded to two questionnaires, and then FeNO levels were measured by an online method with electrochemical analyzer (Medisoft, Sorinnes [Dinant], Belgium). Anthropometric and spirometric data were collected. Simple and a multiple linear regressions were determined. The 95% confidence interval (95% CI) and upper limit of normal (ULN) were defined.
  
  
  RESULTS
  Two hundred eleven children (107 boys) were retained. Anthropometric data, gender, socioeconomic level, obesity or puberty status, and sports activity were not independent influencing variables. Total sample FeNO data appeared to be influenced only by maximum mid expiratory flow (l sec(-1) ; r(2)  = 0.0236, P = 0.0516). For boys, only 1st second forced expiratory volume (l) explains a slight (r(2)  = 0.0451) but significant FeNO variability (P = 0.0281). For girls, FeNO was not significantly correlated with any children determined data. For North African/Arab children, FeNO values were significantly lower than in other populations and the available published FeNO norms did not reliably predict FeNO in our population. The mean ± SD (95% CI ULN, minimum-maximum) of FeNO (ppb) for the total sample was 5.0 ± 2.9 (5.4, 1.0-17.0). For North African, Arab children of any age, any FeNO value greater than 17.0 ppb may be considered abnormal. Finally, in an additional group of children prospectively assessed, we found no child with a FeNO higher than 17.0 ppb.
  
  
  CONCLUSIONS
  Our FeNO norms enrich the global repository of FeNO norms the pediatrician can use to choose the most appropriate norms based on children's location or ethnicity.
authors.affiliation: Service of Physiology and Functional Explorations, Farhat HACHED Hospital, Sousse, Tunisia; Laboratory of Physiology, Faculty of Medicine of Sousse, University of Sousse, Sousse, Tunisia.
authors.forename: Sonia
authors.initials: S
authors.lastname: Rouatbi
authors.forename: Ashraf
authors.initials: A
authors.lastname: Alqodwa
authors.forename: Samia
authors.initials: S
authors.lastname: Ben Mdella
authors.forename: Helmi
authors.initials: H
authors.lastname: Ben Saad
mesh_terms: D000293:Adolescent; D044383:Black People; D001944:Breath Tests / Q000379:methods*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008168:Lung / Q000502:physiology*; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D012016:Reference Values; D012044:Regression Analysis; D015203:Reproducibility of Results; D013147:Spirometry; D011795:Surveys and Questionnaires; D014416:Tunisia
chemical_list: D009569:Nitric Oxide