Measurement of dialysate electrolyte concentrations using biochemical auto‒analyzer and blood gas analyzer

Abstract

[Purpose] We considered how to interpret the values of dialysate electrolytes obtained using a blood gas analyzer (GAS). [Method] The final electrolyte concentrations of Kindaly 4E (K.4E), prepared so that the measured value was the same as the theoretical value, and Kindaly AF‒4(KAF4), prepared according to the instructions for use, were measured using a biochemical auto‒analyzer (BAA) and GAS. [Results] Na, K, and Cl were significantly higher using GAS than BAA. Na‒Cl‒0.25 in K.4E, which represents HCO₃, was 27.5 mmol/L, the same as the theoretical value. HCO₃ (24.45 mmol/L) and iCa (1.19 mmol/L) using GAS were significantly lower than the theoretical values. [Discussion] Since dialysate does not contain solid components such as proteins and lipids, Na, K, and Cl values using BAA, which are calibrated with normal serum, are lower than those using GAS. The difference between Na‒Cl‒0.25 using BAA and HCO₃ using GAS is considered to be due to the fact that Na, K, and Cl measured using the ion selective electrode method (ISE) represent total amounts, while Ca and HCO₃ measured by GAS represent ionized amounts. [Conclusion] Dialysis fluid electrolyte concentrations should be considered in terms of ion amounts.