The burden of pediatric asthma remains high with one-third of patients being 
under- or overtreated because of the unique challenges in the assessment and 
management of childhood asthma. Until recently, there has been no point of care 
tool for assessing the underlying airway inflammation (i.e., inflammometry) in 
asthma. Recently, fractional exhaled nitric oxide (FeNO) has emerged as an 
important biomarker for the assessment and management of asthma. Recent evidence 
indicates that FeNO identifies T-helper cell type 2 (Th2)–mediated airway 
inflammation with a high positive and negative predictive value for identifying 
corticosteroid responsive airway inflammation. This article examines the 
evidence for FeNO as a predictor of Th2-mediated inhaled corticosteroid (ICS) 
responsive airway inflammation and reviews recent studies evaluating the role of 
FeNO, whether helpful or not, in the assessment and management of pediatric 
asthma. FeNO is a reliable adjunct to traditional tests in the assessment of 
suspected asthma. Importantly, it is useful for identifying and for excluding 
ICS-responsive airway inflammation. Although individual study results have 
varied, collectively, asthma managed using FeNO is associated with lower 
exacerbation rates compared with clinical algorithms alone. Finally, FeNO may be 
useful in identifying patients at risk for future impairment or loss of asthma 
control during reduction/cessation of ICS treatment. FeNO testing has an 
important role in the assessment of pediatric patients with suspected asthma and 
in the management of pediatric patients with established asthma. Additional 
studies will continue to define the exact role of FeNO testing in pediatric 
asthma.