Longitudinal measurements of exhaled nitric oxide in children–what is a significant change in FENO?



Steve Turner, Department of Child Health, Royal Aberdeen Children's Hospital, Foresterhill, Aberdeen AB25 2ZD, UK

Tel.: +44 (0)1224 438470

Fax: +44 (0)1224 438469

E-mail: s.w.turner@abdn.ac.uk



The principle aim of this study was to describe the variability of exhaled nitric oxide (FENO) concentrations over 10 months in children with and without asthma.


FENO was measured on six occasions at 2-month intervals in a community-based cohort of children with and without asthma.


There were 178 children recruited, 47 had asthma, mean age 9.6 yr. A total of 851 FENO measurements were made. The change in FENO values was positively associated with the initial FENO concentration (p < 0.001) and duration between paired measurements (p = 0.016) but not asthma diagnosis; there was an interaction between initial FENO and duration between measurements. As an approximate rule-of-thumb, a child's FENO may rise by up to 100% of their current FENO over 2 and 4 months, independent of asthma.


Both the baseline FENO and interval between repeated FENO measurements are relevant to FENO values, independent of asthma. These findings may be useful to clinical interpretation of FENO results in children.