Sodium Potassium & Chlorides are consider as electrolytes testing.
Direct method, Indirect method, and Enzymatic methods use to assay the electrolytes level in serum
Direct & Indirect methods are the 2 main method
Indirect ISE is more commonly used in high throughput fully automated analyzers in the laboratory. Direct ISE is usually available at the point of care instruments & some low throughput biochemistry analyzers.