Reference values for exhaled nitric oxide in healthy children aged 6-18 years in China: a cross-sectional,...

The reference values of eNO have certain differences among people of different countries and races. We aimed to obtain the reference value of eNO in healthy children and adolescents (6-18 years old) in China and to explore the associations between the reference values with ages, gender, heights, BMI, and regions.

We measured FeNO₅₀ levels in 5949 healthy Chinese children and adolescents, FeNO₂₀₀ and CaNO levels in 658 participants from 16 provinces of 7 administrative areas in China aged 6-18. All persons were studied after obtaining informed consent from children and their parents.

The mean FeNO₅₀ of 5949 Chinese children and adolescents aged 6-18 years was 14.1 ppb, with a 95% confidence interval of 1-38.1 ppb. The mean FeNO₂₀₀ of 658 persons was 6.9 ppb with a 95% upper confidence interval of 15.0 ppb, and the mean CaNO was 3.0 ppb with a 95% upper confidence interval of 11.2 ppb. In the 6-11 age group, age and height were correlated with the logarithm of FeNO₅₀ (P < 0.001, P < 0.05). There was no significant correlation between the logarithm of FeNO₂₀₀ and gender, age, height and BMI (all P > 0.05). The logarithm of CaNO was correlated with gender (P < 0.05). In the 12-18 age group, gender, height, and region were correlated with the logarithm of FeNO₅₀ (all P < 0.001). There was only a weak correlation between the logarithm of FeNO₂₀₀ and height (P < 0.001). The logarithm of CaNO was negatively correlated with age (P < 0.05).

Higher FeNO₅₀, FeNO₂₀₀ and CaNO values were found in healthy children and adolescents in China compared with foreign reports, and is affected by age, height, gender, and region. This study provides useful references for clinical application of eNO in children, especially Asian children.