Measurement of nasal potential difference in various forms of atypical or borderline cystic fibrosis

Measurement of nasal potential difference (NPD) was proved to be a useful tool in the diagnosis of cystic fibrosis (CF). In these patients NPD measurement allows to evaluate the different ion transport abnormalities in airway epithelia, i.e. increased sodium permeability and defective chloride conductance. For these reasons this test is used both for clinical purposes, such as the diagnosis of CF in difficult cases, and for research studies, i.e., in the attempt to correct the basic defect with new molecular therapies and gene transfer. In most cases the diagnosis of CF is achieved by means of the sweat test or DNA analysis, and therefore NPD measurement is seldom necessary for this purpose. However, in some patients with symptoms of the disease, the sweat test can be normal, or borderline, and DNA analysis.