THE SWEAT TEST FOR QUANTITATION OF ELECTROLYTES - A CHALLENGE IN PRECISION

The sweat test, a quantitative analysis of electrolytes in sweat, is t he most valuable and widely used laboratory test for the diagnosis of cystic fibrosis. Despite its importance, this test is performed in onl y 19% of US laboratories, according to a recent survey by the college of American Pathologists. The sweat test's reliability may be in jeopa rdy owing to several factors, including a lack of uniformity in the pr eanalytic pilocarpine iontophoresis stimulation and subsequent sweat c ollection, and in the analytic procedures for sweat electrolytes. This article reviews the quantitative analysis of sweat electrolytes, with emphasis on quality assurance and accuracy of techniques.