Nasal nitric oxide is dependent on sinus obstruction in allergic rhinitis.

OBJECTIVES/HYPOTHESIS: The aim of this study was to evaluate the associations between nasal nitric oxide and nasal symptoms, sinus opacification, and markers of allergic inflammation in allergic and in nonallergic rhinitis while taking into account the effect of sinus obstruction.

STUDY

DESIGN

We studied 175 young adult subjects divided into three groups: 1) allergic rhinitis, 2) nonallergic rhinitis, and 3) controls.

METHODS

We measured nasal nitric oxide using the breath-holding method and exhaled nitric oxide and scored semiquantitatively nasal computed tomography scans for opacification and obstruction. We also assessed the visual analogue scores of nasal symptoms, eosinophil count, and interleukin-13 mRNA levels in nasal biopsies.

RESULTS

The level of nasal nitric oxide correlated with exhaled nitric oxide (r = 0.377, P < .001). In allergic rhinitis, nasal nitric oxide was elevated when compared to the controls, and an inverse correlation existed between the nasal nitric oxide level and sinus ostial obstruction (r = -0.272, P = .013). In nonallergic rhinitis, the level of nasal nitric oxide was similar to that of the controls. In allergic rhinitis, nasal nitric oxide correlated positively with the opacification score (r = 0.250, P = .033) and the nasal eosinophil count (r = 0.293, P = .030) of patients without a marked sinus ostial obstruction.

CONCLUSIONS

Sinus ostial obstruction lowers the level of nasal nitric oxide and reduces its value as an indicator of allergic mucosal inflammation. A high nasal nitric oxide level may be a useful marker of eosinophilic inflammation in the nasal cavity and indicate the absence of marked sinus ostial obstruction.

LEVEL OF EVIDENCE: 3b.