Comparison of the chloride electrode and gravimetric chloride titration sweat tests

The chloride electrode sweat test and gravimetric chloride titration technic are compared. The two technics gave comparable mean values, ogives, equivalent points, and overlap for patients with cystic fibrosis and healthy subjects. As a single test with either technic has an unacceptable risk for false-positive or false-negative results, tests should always be done in pairs. A statistical interpretation technic based on prevalence and technical variability of the two tests will decrease the number of undiagnosed subjects and will define probability of cystic fibrosis in the undiagnosed group.