DETERMINATION OF SODIUM, POTASSIUM AND CHLORIDE IN SERUM OR PLASMA

The Boehringer enzymatic reagents for Na, K and Cl determination on a Hitachi 717 automatic analyser at 37 degrees C were evaluated. Except for Na, the within-run and between-run precision assays gave CV within the SFBC ranges but were higher than those of the comparison analysers : Ektachem 500 Kokak, Dimension Ars Du Pont-De-Nemours and flame photometry. The linear ranges were larger than the usual clinical results. Accuracy, estimated from human controls, was 99 to 103% for Na and K, and 105% for Cl. Comparison of plasma from 102 to 152 patients showed a good concordance for sodium with the Dimension ARS (y = 1x + 0). On the contrary, with Ektachem Kodak, differences appeared particularly for high values (y = 0.91x + 13.6). For potassium, the concordance was good with flame photometry (y = 1x + 0.1) and Ektachem Kodak (y = 0.94x - 0.16). For chloride, comparison was satisfactory except for high values which were underestimated by the enzymatic method: Dimension ARS (y = 1.03x - 4.8), Ektachem Kodak (y = 0.91x + 9.8). The enzymatic methods were very easy to perform m and can be adapted on any autoanalyser ar 37 degrees C. We conclude that they are suitable for routine clinical determination. Urinary assays are currently being developed.