Exhaled nitric oxide and its long-term variation in healthy non-smoking subjects.
Exhaled nitric oxide (NOexp) is an indicator of inflammation in the airways. Reference values obtained from healthy adults or information on long-term variation of NOexp are not yet available. The aims of this pilot study were to collect values of NOexp from a selected group of healthy adults and to assess their long-term variation. We studied 26 healthy subjects (age 21-48, 16 male, 10 female) with normal findings in flow-volume spirometry, pulmonary diffusing capacity, relative amount of blood eosinophils, chest X-ray and ECG at rest. NOexp was determined according to the European Respiratory Society guidelines during slow expiration against an airflow resistance. The measurements were repeated after 7 (n = 13) and 23 days (n = 17). The mean value of NOexp (n = 26) was 6.9 ng g-1 (95% confidence interval, 6.0-7.9 ng g-1). The upper limit of intra-individual variation (+2 SD) was 11.9 ng g-1 and the lower limit (-2 SD) 1.9 ng g-1, respectively. The mean (SD) value of NO production (NO output) was 39.1 pmol s-1 (20 pmol s-1). We found no correlation between NOexp and age (r = -0.06, P = 0.78) and no association of NOexp with the gender (male vs. female, P = 0.40). The intraindividual coefficient of variation (CoV) was 15.8% of NOexp and 20.7% of NO output within the interval of 7 days. CoV was 16.8% of NOexp and 18% of NO output within the interval 23 days. The results suggest that NOexp values over 12 ng g-1 are abnormally high in healthy subjects. According to the results the change of NOexp by 30-35% or more within the interval of 1-3 weeks would be abnormal.
Ekroos
H
H
Laboratory Department, Helsinki University Central Hospital, Finland.
Tuominen
J
J
Sovijärvi
A R
AR
D000328:Adult; D001944:Breath Tests; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D011014:Pneumonia / Q000175:diagnosis / Q000378:metabolism; D012016:Reference Values; D012907:Smoking; D013147:Spirometry / Q000592:standards*
D009569:Nitric Oxide