Background and aims Congenital and hereditary diseases of respiratory system are often accompanied by nonspecific symptoms, that result in late diagnosis and time-lag therapy. In some cases, such diseases have symptoms, similar to asthma, so children are wrong diagnosed and do not receive appropriate treatment for a long time. Aim: to define the informative value of measurement of exhaled nitric oxide (FeNO) as a non-invasive screening method for patients with pathology of pulmonary system.

Methods 598 children (from 4 to 17 y.o.) were examined at Scientific Centre of Children’s Health from 01.01.2012 to 11.06.2016. The level of FeNO was determined by portable hand held monitor using, unit ppb (parts per billion).

Results 557 patients (93.14%) were diagnosed with asthma of different severity. Variation of level of FeNO depended on asthma severity and control. FeNO was normal or elevated (from 5 to 233 ppb). In 41 (6.8%) patients the level of FeNO was low (<5 ppb): 25 children (61%) with cystic fibrosis (CF), 5 (12%) with congenital lung malformations (CLM) and 11 (27%) with primary ciliary dyskinesia (PCD). The mean of FeNO level in children with CLM was 2,616±1,804, with CF: 3,27±3,07, with PCD: 0,88±0,53. FeNO level in children with PCD was lower than in children with CF (p<0.05).

Conclusions The finding data indicate the possibility of using of FeNO level evaluation as a non-invasive screening method in the complex differential diagnostics of pulmonary system pathology in children.