Establishing normative nasal nitric oxide values in infants.

Introduction: Primary ciliary dyskinesia (PCD), a disease of impaired respiratory cilia motility, is often difficult to diagnose. Recent studies show low nasal nitric oxide (nNO) is closely linked to PCD, allowing the use of nNO measurement for PCD assessments. Nasal NO cutoff values for PCD are stratified by age, given nNO levels normally increase with age. However, normative values for nNO have not been established for infants less than 1 year old. In this study, we aim to establish normative values for nNO in infants and determine their utility in guiding infant PCD assessment.

Methods And Results: We obtained 42 nNO values from infants less than 1 year old without a history of PCD or recurrent sinopulmonary disease. Using regression analysis, we estimated the mean age-adjusted nNO values and established a 95% prediction interval (PI) for normal nNO. Using these findings, we were able to show 14 of 15 infant PCD patients had abnormally low nNO with values below the 95% PI.

Conclusions: In this study we determined a regression model that best fits normative nNO values for infants less than 1 year old. This model identified the majority of PCD infants as having abnormally low nNO. These findings suggest nNO measurement can help guide PCD assessment in infants, and perhaps other pulmonary diseases with a link to low nNO. With early assessments, earlier clinical intervention may be possible to slow disease progression and help reduce pulmonary morbidity.