Exhaled nitric oxide - circadian variations in healthy subjects.
OBJECTIVE
Exhaled nitric oxide (eNO) has been suggested as a marker of airway inflammatory diseases. The level of eNO is influenced by many various factor including age, sex, menstrual cycle, exercise, food, drugs, etc. The aim of our study was to investigate a potential influence of circadian variation on eNO level in healthy subjects.


METHODS
Measurements were performed in 44 women and 10 men, non-smokers, without respiratory tract infection in last 2 weeks. The eNO was detected at 4-hour intervals from 6 a.m. to 10 p.m. using an NIOX analyzer. We followed the ATS/ERS guidelines for eNO measurement and analysis.


RESULTS
Peak of eNO levels were observed at 10 a.m. (11.1 +/- 7.2 ppb), the lowest value was detected at 10 p.m. (10.0 +/- 5.8 ppb). The difference was statistically significant (paired t-test, P<0.001).


CONCLUSIONS
The daily variations in eNO, with the peak in the morning hours, could be of importance in clinical practice regarding the choice of optimal time for monitoring eNO in patients with respiratory disease.
Antosova
M
M
Institute of Pharmacology, Jessenius Faculty of Medicine, Sklabinska 26, Martin 03601, Slovakia. Antosova@jfmed.uniba.sk
Bencova
A
A
Psenkova
A
A
Herle
D
D
Rozborilova
E
E
D000328:Adult; D001944:Breath Tests; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis*
D009569:Nitric Oxide