title: Relationship between exhaled nitric oxide and atopy in Asian young adults.
abstract: OBJECTIVE
  The relationship between exhaled nitric oxide and atopy is controversial. The aim of this study was to determine the relationship between exhaled nitric oxide (FE(NO)) and atopy in Asian young adults.
  
  
  METHODS
  Subjects were assessed by: (i) the International Study of Asthma and Allergies in Childhood questionnaire to differentiate asthmatic from nonasthmatic and rhinitis from non-rhinitis subjects; (ii) skin prick testing to 10 allergens; and (iii) FE(NO) measurements performed online at a flow rate of 50 mL/s.
  
  
  RESULTS
  Complete results were available for 84 subjects. FE(NO) values were highest in atopic asthmatics (n = 34; median FE(NO), 59.8 p.p.b.; interquartile range, 30.4-85.5 p.p.b), followed by atopic nonasthmatics (n = 34; median, 38.4 p.p.b.; range, 16.7-49.3 p.p.b), nonatopic asthmatics (n = 5; median, 19.1 p.p.b.; range, 17.9-33.4 p.p.b), and lowest in nonatopic nonasthmatics (n = 11; median, 15.7 p.p.b.; range, 11.5-21.7 p.p.b). FE(NO) values were significantly higher in atopic (n = 68; median, 44.7 p.p.b.; range, 27.3-75.2 p.p.b) compared to nonatopic subjects (n = 16; median, 17.0 p.p.b.; range, 11.7-23.8 p.p.b.; P < 0.0001), regardless of asthma and rhinitis status. FE(NO) levels correlated with the severity of atopy (wheal size) for both asthmatic (r = 0.44, P = 0.005) and nonasthmatic subjects (r = 0.48, P = 0.001). There was no significant difference in FE(NO) levels between nonatopic asthmatics and nonatopic nonasthmatic subjects (P = 0.25).
  
  
  CONCLUSIONS
  Increased FE(NO) levels are more reflective of atopy rather than asthma, and increased nitric oxide production may be predominantly a feature of atopy in asthmatics.
authors.affiliation: Paediatric Pulmonary, Sleep and Critical Care Service, The Children's Medical Institute, Department of Paediatrics, National University Hospital, Singapore.
authors.forename: Seo Yi
authors.initials: SY
authors.lastname: Chng
authors.forename: Hugo P
authors.initials: HP
authors.lastname: Van Bever
authors.forename: Derrick
authors.initials: D
authors.lastname: Lian
authors.forename: Shan Xian
authors.initials: SX
authors.lastname: Lee
authors.forename: Xin Ni
authors.initials: XN
authors.lastname: Xu
authors.forename: Xiao Shan
authors.initials: XS
authors.lastname: Wang
authors.forename: Daniel Yam Thiam
authors.initials: DY
authors.lastname: Goh
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens; D001249:Asthma / Q000378:metabolism; D045853:Exhalation / Q000502:physiology*; D005260:Female; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000378:metabolism*; D007428:Intradermal Tests; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*; D012221:Rhinitis, Allergic, Perennial / Q000378:metabolism; D006255:Rhinitis, Allergic, Seasonal / Q000378:metabolism; D012846:Singapore; D013147:Spirometry / Q000379:methods
chemical_list: D000485:Allergens; D009569:Nitric Oxide