Exhaled and nasal NO measurement: NO in your breath doesn’t imply a negative attitude!

Measurement of exhaled nitric oxide (NO) and nasal nitric oxide commenced in the 1990s shortly after the scientific world learned about the endogenous production of NO and its multiple roles in physiologic and pathologic processes. Exhaled NO is an established approved clinical test in asthma that can cast light on eosinophilic airway inflammation and the response to anti-inflammatory medications e.g., inhaled corticosteroids. Nasal NO which is extremely low in primary ciliary dyskinesia is an established screening test for this condition. This review is a high-level practical guide for those wishing to use exhaled and nasal NO for research and clinical application.