Increasing Glucose Concentrations Interfere with Estimation of Electrolytes by Indirect Ion Selective Electrode...

Area of Science:

• Clinical Chemistry
• Analytical Chemistry
• Biomedical Science

Background:

• Electrolyte estimation using ion-selective electrodes (ISE) is standard in clinical laboratories.
• Potential interferents, including proteins, lipids, and drugs, can impact ISE results.
• The effect of hyperglycemia on electrolyte measurements by different ISE methods requires further investigation.

Purpose of the Study:

• To investigate the impact of varying glucose concentrations on the accuracy of sodium (Na+), potassium (K+), and chloride (Cl-) estimations.
• To compare the performance of direct and indirect ISE methods under conditions of high glucose levels.
• To assess interference in both serum and urine samples.

Main Methods:

• Pooled human serum and 24-hour urine samples were spiked with glucose to achieve concentrations from approximately 100 to 5000 mg/dL.
• Electrolyte levels (Na+, K+, Cl-) were measured using both direct and indirect ISE analyzers.
• Statistical analysis included ANOVA and Pearson's correlation to evaluate the data.

Main Results:

• Indirect ISE measurements for Na+ and Cl- were consistently higher than direct ISE measurements.
• Significant differences in Na+ and Cl- estimations by indirect ISE were observed at glucose concentrations ≥2486 mg/dL in serum and ≥2104 mg/dL in urine.
• High glucose concentrations showed a significant negative correlation with Na+ and Cl- estimation by indirect ISE, particularly above 2000 mg/dL. K+ measurements were unaffected.
• Direct ISE methods did not show significant interference from elevated glucose levels.

Conclusions:

• High glucose concentrations significantly interfere with the estimation of sodium and chloride using indirect ISE methods in both serum and urine.
• Direct ISE methods appear to be more robust against glucose interference.
• Clinical laboratories should be aware of potential inaccuracies in electrolyte measurements during hyperglycemia, especially when using indirect ISE techniques.