Nitric oxide metabolites in nasal lavage fluid before and after treatment in patients with allergic rhinitis and their correlation with clinical findings

Allergic rhinitis (AR) is a quite common ENT disease with ever increasing prevalence. There are still some aspects of AR physiopathogenesis that are still not completely understood. Recent studies indicate that nitric oxide (NO) is one of the mediators involved in this complex and intertwined pathophysiological steps, and increased nasal NO levels have been shown in AR. This study aims to investigate whether there is an increase in nasal NO levels in patients with AR, to determine the effects of different drug groups used in treatment on nasal NO levels, and to examine whether a correlation exists between NO levels and the clinical parameters. The study included 60 patients who had active complaints and positive prick test results and did not receive pharmacological treatment for AR within the last 3 weeks,along with a control group comprised of 25 healthy individuals. Smokers, those who had upper respiratory tract infection within the last 10 days or history of asthma were excluded from the study. All the patients and the control group included in the study underwent ENT examination, and a survey form including information on symptoms and examination scores were filled. In addition, eosinophil ratios, total and specific IgE levels were measured both in whole blood and in nasal smear, and prick test was applied to all patients. In addition to all these investigations, levels of NO metabolites (nitrite and nitrate) were measured in nasal lavage samples obtained from patients prior to treatment and from the control group, with specific assays using colorimetric method. The patients were randomly assigned to monthly local nasal corticosteroid (CS) (triamcinolone acetonide 1x2 puff/day) group and oral antihistaminic (fexofenadine 1x120 mg/day) group, with an equal number of patients assigned to each group. The same procedures were repeated after the treatment. Due to patient non-compliance, 6 patients from the antihistaminic group and 10 patients from the CS group were dropped out of the study. Consequently, the study was completed with a patient group comprised of 44 patients. In the patient group, most common hypersensitivity reactions were against house dust mite (88.6%), grass grain pollen (36.4%) and early flowering tree pollen (33.4%). The pre-treatment nitrite+nitrate levels in the patient group (1.92±1.20 mg/l) was significantly higher when compared to the control group (1.38±0.78 mg/l). In the patient group, nitrite+nitrate level showed a significant decrease after treatment (1.92±1.20 ml/l vs 1.52±0.85 mg/l). While there was no difference between pre-treatment nitrite+nitrate levels of oral antihistaminic and local CS groups, nitrite+nitrate level was significantly lower in the antihistaminic group after treatment. Post-treatment symptom and examination scores and nasal eosinophil levels were also significantly lower than pre-treatment values. However, nasal NO levels did not show a direct correlation between symptom and examination scores and nasal smear eosinophil ratios in AR patients.