Sodium, Blood

Additional Information:

UFHPL Epic order code: LAB122

CPT Code(s):


Collection Procedure:

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

Specimen Requirements:

Type: Peripheral blood


  • Serum, gel
  • Plasma, gel

Sample Volume: 0.5mL serum

Stability (collection to shipping of the sample):

  • Refrigerated: 1 week

Unacceptable Conditions: Moderate-to-gross hemolysis

Specimen Retention Time: 5 days


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.


Within 24 hours

Reference Values:

136 – 145 mEq/L