Potassium, Blood

The determination of electrolytes is one of the most important functions in the clinical laboratory. Methods of determining electrolytes include emission spectrophotometry, flame spectrophotometry, neutron activation analysis, atomic absorption spectroscopy and ion selective electrodes. The ISE module for Na+, K+, and Cl- employs crown ether membrane electrodes for sodium and potassium and a molecular oriented PVC membrane for chloride that are specific for each ion of interest in the sample. An electrical potential is developed according to the Nernst Equation for a specific ion. When compared to the Internal Reference Solution, this electrical potential is translated into voltage and then into the ion concentration of the sample.
Monday - Friday
Within 24 hours
Purpose and principle: 
Electrolytes affect most metabolic processes. They serve to maintain osmotic pressure and hydration of various body fluid compartments, proper body pH and regulation of appropriate heart and muscle functions. Electrolytes are also involved in oxidation-reduction reactions and participate as essential parts, or co-factors, in enzyme reactions.
Specimen Requirements: 
Type: Peripheral blood

  • Serum, gel
  • Plasma, gel

Sample Volume: 0.5 mL serum

Stability (collection to time of analysis/testing):
  • Refrigerated: 1 week

Unacceptable Conditions: Moderate-to-gross hemolysis

Specimen Retention Time: 5 days
Reference Values: 
3.5 - 5.1 mEq/L
CPT Code (s): 

UFHPL Test #: 20350

UFHPL Epic order code: LAB114

Collection procedure: 
Serum gel tubes should be centrifuged within 2 hours of collection.
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