Objectives: To demonstrate the value of nasal transepithelial potential difference measurements in the diagnosis and assessment of therapeutic effect in cystic fibrosis.
Method: Nasal transepithelial potential difference was measured in 50 patients with cystic fibrosis (mean age 10 years) and 21 controls (mean age 8 years).
Results: There was a very significant increase in nasal transepithelial potential in cystic fibrosis patients (-28 +/- 8 mv) compared with controls (-8 +/- 3 mv) (p < 0.0001). The sensitivity and specificity of this test for the diagnosis of cystic fibrosis were 92% and 95% respectively. Nasal transepithelial potential difference was positively correlated with age (r = 0.43; p < 0.002) in cystic fibrosis patients but no correlation was found in controls. There was no significant difference in potential differences as a function of sex or Delta F508 genotype (homozygous vs heterozygous; Delta F508 vs non-Delta F508).
Conclusion: These findings demonstrated the value of transepithelial potential difference in the diagnosis of cystic fibrosis and emphasized its capacity to assess the effect of new therapeutic protocols aimed at modifying C1- and Na+ ion transport. It could be particularly helpful for the interpretation of doubtful sweat tests.