Reference values of exhaled nitric oxide in healthy Asian children aged 5 to 18 years

Area of Science:

• Pediatric Pulmonology
• Environmental Health
• Allergy and Immunology

Background:

• Exhaled nitric oxide (F(eNO)) is a marker of airway inflammation.
• Establishing ethnic-specific reference values for F(eNO) in children is crucial for accurate diagnosis.
• Previous studies suggest variations in F(eNO) based on ethnicity.

Purpose of the Study:

• To determine reference values for F(eNO) in healthy Asian children aged 5-18 years.
• To identify key determinants of F(eNO) in this population.
• To compare F(eNO) values with those previously reported for Caucasian children.

Main Methods:

• A cross-sectional study involving 693 healthy Asian children.
• Standardized single-breath F(eNO) measurements at 50 mL·s(-1) exhalation flow.
• Data collection included questionnaires, anthropometrics, spirometry, and immunoglobulin E (IgE) levels.

Main Results:

• Geometric mean F(eNO) was 13.7 ppb (upper 95% CI: 49.7 ppb) in healthy children.
• F(eNO) showed positive associations with age, allergic sensitization, total IgE, ambient nitric oxide, afternoon testing, and recent water intake.
• F(eNO) was negatively associated with weight; age was the best predictor in non-sensitized children.

Conclusions:

• Upper limits of normal F(eNO) in Asian children range from 21 ppb (young children) to 39 ppb (adolescents).
• Ethnicity, age, allergic sensitization, IgE levels, ambient nitric oxide, time of day, water intake, and weight are significant determinants of F(eNO).
• Asian children exhibit higher predicted F(eNO) values compared to Caucasian children, highlighting the need for ethnic-specific reference ranges.