Sweat chloride: quantitative patch for collection and measurement.
OBJECTIVE
To compare two quantitative pilocarpine iontophoresis tests for sweat chloride.


METHODS
Simultaneous right and left arm sweat tests were done with the Gibson/Cooke and the CF quantum technologies.


METHODS
Sweat tests were performed in a quality controlled cystic fibrosis (CF) sweat test laboratory by an experienced technologist at the University of Minnesota CF Center.


METHODS
Patients referred for sweat tests as well as volunteer CF and control subjects (50 CF and 114 'normals') were tested.


METHODS
Standard procedures were used for the Gibson/Cooke test (GCST). The manufacturer of the CF quantum test (CFQT) provided factory standardized materials.


METHODS
Sweat chloride concentration, test time, failed tests, sensitivity, specificity, and cost.


RESULTS
Duplicate test comparing the CFQT and the GCST revealed good comparability (R2 = 0.9434). Sensitivity and specificity of the two methods are comparable at about 94% and 99% respectively. Rate of failed tests was 1% for the CFQT and 15% for the GCST. The CFQT and the GCST are comparable (R2 = 0.9434). Sensitivity (94%) and specificity (99%) are the same for both tests.


CONCLUSIONS
The CFQT method is equal in accuracy and reliability to the more labor-intensive and costly GCST. Advantages of the CFQT are: the small sample size required (three to ten mg), decreased operator dependence, simpler to perform, and requires less equipment. It could be used in a clinic setting to diagnose CF in patients with suggestive symptoms.
Warwick
W J
WJ
University of Minnesota Medical School, 420 Delaware St SE, Box 742, Minneapolis, MN 55455, USA. warwi001@tc.umn.edu
Hansen
L G
LG
Brown
I V
IV
Laine
W C
WC
Hansen
K L
KL
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D002712:Chlorides / Q000032:analysis*; D003550:Cystic Fibrosis / Q000175:diagnosis*; D006801:Humans; D007223:Infant; D007478:Iontophoresis; D008875:Middle Aged; D010862:Pilocarpine / Q000008:administration & dosage; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D013542:Sweat / Q000737:chemistry*
D002712:Chlorides; D011933:Reagent Kits, Diagnostic; D010862:Pilocarpine