Nitric oxide: a promising methodological approach in airway diseases.

Nitric oxide (NO) is a potent biological mediator, and has a regulatory role in a wide variety of cellular and tissue functions. In the upper and lower airways, NO has been suggested to be involved in different functions with regulatory, protective, defensive or damaging effects. It is obvious that NO plays an important role in host defense, and is liberated in the nose and the paranasal sinuses. This review aims to highlight some aspects of the origin and function of NO in airway diseases, such as allergic rhinitis, chronic rhinosinusitis with and without nasal polyps, primary ciliary dyskinesia, and cystic fibrosis. In conclusion, NO measurement may be a promising noninvasive diagnostic marker for airway pathologies.