Serum stability of sodium, potasium and chloride concentration in special tubes containing separator and clotting activator

Abstract

The sample stability information provided by the manufacturers is not always confirmed in practice. The electrolyte concentration is one of the most frequently requested laboratory tests. The aim of this study was to evaluate the stability of electrolytes (sodium, potassium and chloride) concentration in sample collected in S-Monovette tubes containing clotting activator and a separator gel.<br>Material and methods. Determination of electrolyte concentration was performed immediately after centrifugation of samples and after 48 and 96 hours of samples storage. The examination was performed using biochemical analyzer AU 480 equipped in ion-selective electrodes (ISE) – indirect potentiometry.<br>Results. The analysis of the results was carried out in relation to normal and pathological values (low and high). There were no significant changes in the concentration of electrolytes examined after 48 and 96 hours of samples storage for normal and low– pathological values. Only in samples with hyperkalemia, the concentration of potassium exceeded the limit of allowable error after 96 hours of samples storage.<br>Conclusions: It is possible to determine sodium, potassium and chloride concentrations up to 96 hours from the collection of samples, in the case of laboratory tests performed using primary samples, with a clotting activator and a separator gel. Only in specimens with hyperkalemia, the potassium concentration can be determined up to 48 hours.