Fractional exhaled nitric oxide measurements are most closely associated with allergic sensitization in school-age children.

Background: Factors affecting fractional exhaled nitric oxide (FeNO) in early childhood are incompletely understood.

Objective: To examine the relationships between FeNO and allergic sensitization, total IgE, atopic dermatitis, rhinitis, asthma, and lung function (spirometry) in children.

Methods: Children at high risk of asthma and other allergic diseases because of parental history were enrolled at birth and followed prospectively.