Nasal nitric oxide measurements to screen children for primary ciliary dyskinesia

Study objective: To examine the usefulness of exhaled and nasal nitric oxide (NO) measurements to detect primary ciliary dyskinesia (PCD) in children. Design and methods: The study population consisted of 34 children with symptoms suggestive of PCD who were previously referred to our pediatric university respiratory disease clinic for a diagnostic workup including analysis of ciliary structure and function by respiratory mucosal biopsy. PCD was diagnosed in 17 of the 34 children according to the ciliary biopsy results. Measurements of nasal and exhaled NO were performed according to European Respiratory Society and American Thoracic Society guidelines in the patients with and without biopsy-proven PCD, and also in 24 healthy age-matched subjects. Results: Nasal NO was significantly lower in those children with proven PCD (geometric mean; 13.7 parts per billion [ppb]), compared to those who had negative biopsy results (132.7 ppb) and healthy control subjects (223.7 ppb). The measurement of nasal NO in our study population showed, below a cut-off level of <105 ppb, a specificity of 88% for PCD, and positive predictive value of 89%. Nasal NO above a cut-off level of 105 ppb excluded PCD with a 100% certainty. The lower levels of exhaled NO in patients with PCD did not reach statistical significance. Conclusion: The measurement of nasal NO appears to be a useful tool to screen children for PCD and to exclude this disease in those with high nasal NO levels.