A Comparative Analysis of Serum Sodium Level Utilizing Direct and Indirect Ion Selective Electrode in Critically Ill Patients with Hypoalbuminemia: Methodological Insights and Clinical Implications

Abstract

Background: Serum electrolytes are one of the most frequently requested tests in patients from critical care settings. Methods for estimation of serum electrolytes include direct and indirect ion selective electrode (ISE). In case of indirect ISE, the pre-analytical dilution step can result in pseudonormonatremia or pseudohypernatremia in setting of hypoalbuminemia. Discrepancy in sodium results can lead to the misdiagnosis and mismanagement of critically ill patients.

Objective: To evaluate the difference of mean serum sodium level measured by direct and indirect ISE in critically ill patients with hypoalbuminemia.

Study type, settings & duration: This cross-sectional study conducted in Department of Chemical Pathology, Sheikh Zayed Hospital, Rahim Yar Khan from February to August 2022.   

Methodology: A total 408 study subjects aged between 20 to 60 years admitted in intensive care units of Sheikh Zayed hospital Rahim yar khan with serum albumin level <3.5 g/dl were included in study. Serum sodium level was estimated concurrently by both methods for all study subjects satisfying the inclusion criteria. Mean difference of serum sodium level measured by both methods was evaluated to see the statistically significant difference between two methods.

Results: Mean difference of serum sodium level measured by indirect and direct ISE (Indirect ISE-direct ISE) was 4.216±13.571mmol/L with statistically significant difference (p value: 0.000). The difference was not acceptable according to CLIA (Clinical Laboratory Improvement Amendments) requirements for acceptable performance between the methods. Effect of triglyceride was statistically significant for mean difference of serum sodium level ...........