FeNO as biomarker for asthma phenotyping and management.

The current review aims to revisit literature on exhaled nitric oxide (FeNO) in asthma phenotyping and management to clarify the utility of this test in clinical practice. It is increasingly evident that multiple profiles characterize asthma as a complex disease for which is necessary to find tools able to discriminate among these phenotypes to achieve the best therapeutic strategy for all asthmatic patients. Current findings indicate that FeNO, a noninvasive and easy-to-obtain biomarker, can be considered a useful tool in predicting asthma developing and exacerbation, in identifying specific asthma phenotypes, in improving asthma diagnosis and management in a selected population, and in monitoring efficacy of standard corticosteroid and biologic therapy. Based on this evidence, FeNO might become an appropriate tool for physicians to better define specific asthma phenotypes and to better deal with asthma worsening.