Diagnostic efficiency of sweat conductivity testing in cystic fibrosis

Background: Standart method for sweat test is Gibson-Cooke and manuel titration. Measurement of sweat conductivity is an alternative method as it is easier to perform. Aim: To assess the diagnostic efficiency of sweat conductivity values and compare it with other methods. Methods: A total of 188 cases (74 CF and 114 controls) were enrolled. Sweat was collected either with quantitative pilocarpine iontophoresis (QPI) by Gibson-Cooke method followed by chloride concentration measurement by manual titration according to Schales & Schales, or by Macroduct coil system followed either by titrimetric chloride measurement by Sherwood Chloridometer or conductivity measurement by a coulometric end point method (CFΔ Collection System, UTSAT/Turkey). Results: Within-run and between-run imprecisions were determined using control samples with Cl- concentrations of 40, 70 ve 130 mmol/L. ROC analysis was drawn and sensitivity and specificity were above 95% for all three sweat test methods. Conclusion: Conductivity might be as reliable as quantitative sweat chloride analysis to diagnose or exclude CF, and thus its potential as a definitive diagnostic tool for CF should be considered.