Relationship between exhaled nitric oxide and atopy in Asian young adults.
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.
Chng
Seo Yi
SY
Paediatric Pulmonary, Sleep and Critical Care Service, The Children's Medical Institute, Department of Paediatrics, National University Hospital, Singapore.
Van Bever
Hugo P
HP
Lian
Derrick
D
Lee
Shan Xian
SX
Xu
Xin Ni
XN
Wang
Xiao Shan
XS
Goh
Daniel Yam Thiam
DY
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
D000485:Allergens; D009569:Nitric Oxide