Electrolytes Serum or plasma concentrations of these major electrolytes can be measured by ion-specific electrodes or by flame photometry. Measurement of electrolytes by ion-specific electrodes is called potentiometry. There are two types of potentiometry: direct and indirect. Direct potentiometry is utilized by blood gas machines and does not involve sample dilution. Indirect potentiometry is utilized by wet chemistry analyzers, such as the Hitachi 911, and involves sample dilution pre-analysis. This distinction is important as plasma features such as lipemia may interfere with indirect, but not direct, potentiometry. In general, electrolyte levels in blood are influenced by changes in free water and by changes in electrolytes themselves, namely rate of intake, excretion/loss, and translocation within the body. Translocation can occur via movement into or out of cells or into specific fluid compartments, such as a distended abomasum. As electrolytes are essential to proper functioning of cells, the body maintains electrolyte concentrations within fairly narrow limits. Clicking on the above image will provide additional information about the individual electrolytes.

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