Nitric oxide measurement in chronic cough.

Chronic cough is a common symptom-based diagnostic challenge for primary care physicians and respiratory specialists. Measurement of exhaled nitric oxide is a convenient, reproducible, and inexpensive point-of-service test. It can simplify the evaluation process of chronic cough by providing information regarding the state of airway inflammation. If exhaled nitric oxide is elevated, this is predictive of a favorable response to inhaled corticosteroids. This has the effect of reducing empirical trials for cough-variant asthma or eosinophilic bronchitis. The inclusion of exhaled nitric oxide in the diagnostic approach to chronic cough should be considered.