Revisiting the role of exhaled nitric oxide in asthma

Curr Opin Pulm Med. 2014 Jan;20(1):53-9. doi: 10.1097/MCP.0000000000000006.


Purpose of review: This review focuses on the most recent studies investigating fractional nitric oxide concentration in exhaled breath (FeNO) as a useful biomarker for identifying specific phenotypes in asthma and as a tool for asthma diagnosis, monitoring and clinical decision-making.

Recent findings: On the basis of the current literature, it has been highlighted that FeNO is a clinically relevant marker in various clinical aspects of asthma: FeNO is a predictor for developing asthma in persistent rhinitis or in infants with respiratory symptoms; FeNO contributes to identification of asthma phenotypes in both children and adults, also in relation to severity; FeNO is useful in monitoring the effectiveness of inhaled corticosteroids (including compliance) and biologic treatments like omalizumab; FeNO, in conjunction with symptom registration and lung function measurements, contributes to asthma diagnosis and optimizes asthma management.

Summary: FeNO provides further information in distinguishing different phenotypes in asthma, allowing a much more appropriate control of the disease, especially in patients with difficult/severe asthma. In the future, it would be interesting to shed light on the hidden biological mechanisms responsible for low or normal FeNO values in symptomatic asthmatic patients.

Publication types

  • Review

MeSH terms

  • Adrenal Cortex Hormones / therapeutic use
  • Asthma / diagnosis*
  • Asthma / drug therapy
  • Asthma / metabolism*
  • Biomarkers / metabolism
  • Breath Tests
  • Exhalation*
  • Humans
  • Nitric Oxide / metabolism*
  • Phenotype
  • Severity of Illness Index
  • Treatment Outcome


  • Adrenal Cortex Hormones
  • Biomarkers
  • Nitric Oxide