Effect of Age and Eosinophil Number on Fractional Exhaled Nitric Oxide Level in Non-Asthmatic Children in Shanghai

This study aimed to identify the relationship between fractional exhaled nitric oxide (FeNO) level and potential factors in non-asthmatic children from Shanghai, China. From March to April 2012, the school-aged children fulfilling the inclusion criteria were recruited. The FeNO levels of non-asthmatic children were detected by the Nano Coulomb nitric oxide analyzer. Questionnaires were recorded, including personal data, family illness history and daily habits. In addition, not only the number of leukocytes and eosinophils but also the level of hemoglobin in peripheral blood, were measured via the automated blood cell analyzer. All data were statistically analyzed with SPSS version 17.0 software and the correlation of these potential factors with FeNO level was calculated via Kendall's rank correlation. A total of 132 healthy children (aging 6-13 years) were enrolled in Minhang District, Shanghai, China. The mean value of FeNO level was 15.05 ppb. The correlation analyses revealed that age (R=0.190, p=0.029) and eosinophil number (R=0.575, p=0.000) were significantly and positively correlated with FeNO levels. The FeNO levels of individuals aged 10-13 years was significantly higher than those of the individuals aged 6-9 years (22.65±18.82 ppb vs. 15.28 ± 9.78 ppb, p<0.05). However, other potential factors were not significantly correlated with FeNO level. The FeNO levels in healthy school-aged children may reflect airway eosinophilic inflammation levels, and was affected by eosinophil count and age significantly.