Effect of Increasing Glucose Concentration on Estimation of Electrolytes by ion selective electrode

Background The measurement of serum electrolytes like sodium (Na+), potassium (K+) is routinely performed in clinical biochemistry laboratories using ion-selective electrodes (ISE). Aim To minimize error and test the effect of increasing glucose concentration on estimation of sodium and potassium. Materials and Methods Randomly selected sera samples submitted for routine biochemical estimations were pooled for the study. A stock solution of glucose with concentration of 20 g/ dL was prepared by dissolving anhydrous glucose in normal saline (0.9 % NaCl). Next the pooled sera was divided into several aliquots with 1.0 ml sera each and increasing amounts of the stock solution were added to the different aliquots so as to generate glucose concentrations ranging from around 100 mg/dL to about 3000 mg/dL. Results the glucose concentration of different serum aliquots obtained on cobas c311(roche system) were found to rang from 110 to 2577 mg/dl. The mean of sodium by direct ion selective 142±0.52 mmol/l, values showed in significant difference (p=0.320).The mean of sodium by indirect ion selective 143 ± 0.72 mmol/l, values showed significant difference (p< 0.05). And the mean of potassium by direct ion selective 3.54 ±0.29 mmol/l, values showed significant difference (p< 0.05). The mean of potassium by indirect ion selective 3.53±0.26 mmol/l, values showed significant difference (p< 0.05). Conclusions Increasing blood gluose interferance in electrlytes mainly potasssium by both direct and indirect ion selective electrode, whenincreasing glucose potassium decreae significantly No different significant between direct and indirect ion selective electrods in potassium when used cobas c311 and easy lyte.Significant interferance in sodium by indirect ion selective electrodewhile no significant interferance in sodium direct ion selective electrode.Glucose concentration interfer the electrolyte specially potassium in concentration more than 1700 mg/dl by direct and indirect methods.