Patients with allergic rhinitis (AR) show augmented activity of the nitric oxide (NO) metabolism in the inferior turbinate mucosa, similar to that seen in bronchial asthma (BA). We believe that the measurement of nasal fractional exhaled NO (FeNO) can be used as a parameter for the diagnosis and classification of symptomatic AR patients. The purpose of this study was to assess whether nasal FeNO levels can be used as a reliable tool to evaluate the efficacy of intranasal steroids on allergic nasal symptoms.
A total of 10 symptomatic adult AR patients were enrolled in this prospective study. The patients received nasal steroids (fluticasone furoate once daily) for 2 months. Subjective symptoms were recorded on each visit according to the Japanese guidelines for AR. Oral and nasal FeNO measurements were carried out using a handheld electrochemical analyzer according to American Thoracic Society/European Respiratory Society (ATS/ERS) guidelines.
The mean total nasal symptom score significantly decreased from an initial score of 4.4 to 2.38 after 2 months of treatment. The mean oral FeNO level remained unchanged compared with pretreatment baseline levels, however, the mean nasal FeNO level significantly decreased from an initial score of 47.6 ppb to 33.4 ppb after 2 months of treatment.
The attenuated nasal FeNO levels are likely due to the inhibition of inducible nitric oxide synthase isoform induced by corticosteroids, leading to diminished NO production in the inferior turbinate. Our results indicate that nasal FeNO measurement can server as an objective parameter for the diagnosis of AR and for monitoring the therapeutic effects of intranasal steroids.
