VALIDITY OF THE WESCORS SWEAT CONDUCTIVITY ANALYZER FOR THE ASSESSMENT OF SWEAT ELECTROLYTE CONCENTRATIONS

The purpose of this study was to compare the ''NaCl equivalent'' value s determined by the Wescor's sweat conductivity analyzer (Sweat-Chek) with the sweat Na+ and Cl- concentration values measured by convention al methods. The sweat was induced by 60-min exercise and collected by a closed-pouch collector. The ''NaCl equivalent'' values determined by the sweat conductivity analyzer (mean: 75 mmol.L(-1), range: 38 - 122 , n = 72) were significantly P < 0.05) greater than Na+ concentration values (mean: 71 mmol.L(-1), range: 24 - 123, n = 72) measured by flam e photometry and Cl- concentration values (mean: 61 mmol.L(-1), range: 18 - 100, n = 48) measured by coulometric titration. The differences were most accen-tuated for low concentration values. The 95% confidenc e-agreement intervals around the mean differences between methods were 11 mmol.L(-1) (14%) for both Na+ and Cl-. The Sweat-Chek conductivity analyzer is a portable instrument which approximates the actual Na+ a nd Cl- concentrations in sweat but with a positive bias probably due t o the other unmeasured anions present in sweat.