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Sodium ion concentration is measured by indirect potentiometry using two glass sodium electrodes. One of these electrodes will act as the reference electrode. The buffer has a high molar strength which establishes a constant activity coefficient for sodium ions. This calibrates the electrode to concentration values.

Test Utility

Sodium measurement is used in the diagnosis and treatment of electrolyte imbalance.

Specimen Collection and Preparation

Serum or plasma sample in the following tubes:

  • Serum separator tube (gold or tiger top)

  • Lithium Heparin OR Sodium Heparin OR Ammonium Heparin (green top)

Specimen Storage and Stability

Sample should be centrifuged at 3000 rpm for 15 minutes within 2 hours of collection, and plasma separated as soon as possible.

Store serum or plasma samples at the following temperatures:

  • Room temperature: 15°C to 30°C no longer than 8 hours

  • Refrigerated: 2°C to 8°C up to 48 hours

  • Frozen: -20°C or lower for up to 7 days. Samples should only be thawed once.

Specimen Rejection

  • Insufficient sample volume

  • Sample not stored at proper temperature

  • Frozen whole blood

  • Severely hemolyzed samples

  • Severely lipemic specimens

  • Specimen labeled incorrectly or not labeled

  • Potassium oxalate or Sodium fluoride samples

Reference Pages


Monday – Saturday

Result available within 24 hours of receipt in laboratory

NOTE: Specimens are refrigerated (2-8°) for 7 days before disposal

STAT results available within 2 hours of receipt in the laboratory


Vibra Health Laboratory

1307- A, Allen Dr

Troy, MI 48083

(248) 846-0663

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