Determination of Sodium and Potassium Electrolytes in Human Serum by Indirect and Direct ISE Methods in Linical and Biochemical Laboratories

The determination of sodium and potassium electrolytes in human serum requires particular attention, because the alternation of different analyzers/methodologies during the day, in a general hospital. This research compares the data produced by 2 different analyzers that applied different methodologies which are commonly used in clinical chemistry laboratories to measure sodium and potassium ions. Olympus AU640 analyzer (Olympus, Japan) uses indirect ISE method while Microlyte 6.0 analyzer (KONELAB, Finland) uses direct ISE. It is shown that for the potassium a linear fitting model was the most appropriate for data transformation from Olympus AU640 to Microlyte 6.0. Also it is shown that a linear transformation model was not the most appropriate for transformation in the case of sodium concentrations. Finally some tentative conclusions are derived concerning the problem of transferability of results exists when laboratories use the above analyzers for the determination of the electrolytes sodium and potassium.