Olfactory function and nasal nitric oxide

Objective: To determine the relationship between nasal nitric oxide (nNO) concentration and its influence on olfactory function. Setting: Tertiary otolaryngology care centre. Participants: Sixty‐four patients suffering from chronic rhinosinusitis and 20 healthy subjects participated. Study design: Prospective study. Outcome measures: The nNO concentration was measured by chemiluminescence and olfactory thresholds were measured with the phenyl ethanol threshold of the Sniffin’ Sticks. In chronic rhinosinusitis patients this measure was done preoperatively and 3 months after endoscopic sinus surgery. Results: Healthy subjects had significantly higher nNO concentrations and better olfactory thresholds compared to the chronic rhinosinusitis patients, both before and after those had undergone sinus surgery. Olfactory thresholds and nNO concentrations remained unchanged after surgery in the chronic rhinosinusitis group. In the chronic rhinosinusitis group, nNO concentrations correlated positively with the olfactory threshold preoperatively (P