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Test Code 291 Osmolality, Serum

Additional Codes


PowerChart: Osmolality Serum

Epic: LAB107 Osmolality

MA Cerner: Osmolality Level.

Test Method

Freezing Point Osmometer; Osmete II, Precision Systems

Specimen Requirement

0.5 mL serum or plasma is required. Serum and plasma gel tubes are not acceptable. Hemolyzed specimens are not acceptable.

Additional Specimen Collection Information

Collect blood in a lithium heparin, green-top or red-top tube.

  • If sending specimen within 2 hours of collection do not open, send the specimen in the collection tube.
  • If delivery of specimen takes over 2 hours, centrifuge the specimen, then transfer an aliquot of the serum or plasma into a small tube or cup with only a small air space left between the specimen and the cap. Cap tightly and store refrigerated at 2-8°C. Label the specimen appropriately with two identifiers, patient name and another identifier, (patient ID number, DOB, etc.) include date and time of collection and initials of person collecting the specimen.


Testing is performed Monday through Sunday.

Typically completed within 4 hours after the specimen arrives at the testing site.

Reference Values

275-295 mOsm/kg

CPT Code Information

83930 Chemistry: Osmolality; blood

Useful For

Evaluating acutely ill or comatose patients.

LOINC Code Information

2692-2 Osmolality Of Serum Or Plasma