Background: It has been shown that chronic bronchitis, cigarette smoke, hypoxia, and chronic airways inflammation are associated with reduced CFTR function. Primary ciliary dyskinesia (PCD) is characterized by chronic sino-pulmonary disease and chronic bronchiectasis. We have noticed that some patients with PCD have borderline or high sweat chloride test. This may suggest acquired CFTR dysfunction in these patients.
Aim: To analyze CFTR function in a large cohort of PCD patients by measuring sweat chloride and nasal potential difference (NPD), and to compare the results with control individuals and patients with CF.
Methods: 30 PCD patients >6 years treated at our clinic performed sweat test and NPD. For all patients with above normal values in the sweat test and NPD tests, analysis for CFTR mutations or exome analysis was performed.
Results: The mean (±SD) value of sweat chloride of the 30 PCD patients was 51.5±18.6 mmol/L (normal <40mmol/L), 9/30 had abnormal values (>60mmol/L) and 9/30 had normal values. 2/17 patients had abnormal NPD and genetically confirmed PCD.
Conclusions: PCD patients may have abnormal sweat chloride tests; therefore, it is important to perform NPD in patients with abnormal/borderline sweat test in order to differentiate between PCD and CF and to confirm the diagnosis with genetic analysis. It is suggested that PCD should be added to the list of diseases causing false-positive sweat tests. The significance of this reduced CFTR function needs further investigation since new therapies that augment CFTR function may be beneficial in these patients.
