2022 Volume 82 Issue 4 Pages 274-284
Fractional exhaled nitric oxide （FeNO） is a clinically established noninvasive marker of airway inflammation in bronchial asthma. In allergic rhinitis, lower airways contain inflammatory cell infiltrates such as CD4＋ lymphocytes and eosinophils, which are purported to affect the FeNO levels. In this study, we investigated whether exposure to cedar pollen affects the interpretation of FeNO levels and thus improves the accuracy of FeNO clinical test results. Accordingly, FeNO was measured in 14 healthy adults and 33 patients with cedar pollinosis during the pollen-free and dispersal periods from September, 2015, to April, 2016. The allergenic factors were evaluated through various blood tests. Symptoms of rhinitis were also evaluated by calculating the total nasal symptom score. The FeNO level of the healthy group was 17.1ppb and 17.7ppb during the pollen dispersal period and pollen-free period, respectively. Meanwhile, the FeNO level of the pollinosis group was 24.4ppb during the pollen dispersal period and 23.9ppb during the pollen-free period. These findings suggest that there are no seasonal variations in FeNO levels between the pollinosis and healthy groups. Although no significant difference was observed between the two groups in both periods, FeNO in the pollinosis group was consistently above the cutoff value of 22ppb, which was used as a threshold for differentiating between the healthy group and the asthmatic group in both periods. In the specific allergen test administered to cedar pollinosis patients, the positivity rate for cedar was determined to be 100％. However, 97％ of the individuals were also detected as positive for inhalant allergens besides cedar. Various confounding factors, such as smoking and eosinophilic diseases, could contribute to abnormal levels of FeNO. Thus, the seasonal variations in FeNO levels of pollinosis patients should be evaluated and analyzed in a larger cohort of patients to adjust for possible confounding patient data.
