Coulometric titration of sweat collected with the Webster Collection System.

Presented here are chloride results obtained by direct titration of undiluted sweat collected with the Webster Sweat Collection System. Six hundred and thirty-two sweat chloride results were reported on 604 patients. Thirty-six of thirty-nine sweat chloride results of 60 mM or greater were from patients with cystic fibrosis. Three results (61, 63 and 64 mM) were from a 12-year-old female who had one episode of rectal prolapse but after one year does not have clinical evidence of cystic fibrosis. There was one patient with a cystic fibrosis variant with intermediate range sweat chloride. All others in the intermediate range (40-59 mM) did not have cystic fibrosis. One patient with a sweat chloride reported of less than 40 mM was subsequently found to have cystic fibrosis at another institution.