Sodium, Urine

Additional Information:

UFHPL Test #: 20417

CPT Code(s):


Collection Procedure:

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

Specimen Requirements:

Type: 24-hour urine

Stability (collection to shipping of the sample):

  • Refrigerated: 1 week
Unacceptable Conditions: Incomplete collection information



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:

40 – 220 mEq/day

Interpretation Data: