Nasal nitric oxide: longitudinal reproducibility and the effects of a nasal allergen challenge in patients with allergic rhinitis.

Boot JD, de Kam ML, Mascelli MA, Miller B, van Wijk RG, de Groot H, Cohen AF, Diamant Z

Exhaled nitric oxide (eNO) is a validated noninvasive marker of airway inflammation in asthma. In patients with allergic rhinitis (AR), increased levels of nasal nitric oxide (nNO) have also been measured. However, the applicability of nNO as a marker of upper airway inflammation awaits validation.