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Test Code 540 Osmolality, Serum

Specimen Containers and Fixatives

Gold Top Tube (SST)


For add-on testing, refer to link below for acceptable tube types:

Acceptable Tube Types for Chemistry Tests

Specimen Required

NorthShore Lab Services: draw 0.8 mL (0.3 min) blood, centrifuge and submit 0.3 mL (0.1 min) refrigerated serum.

Hospital setting: submit 0.3 mL (0.1 min) blood.


For sample stability, refer to the link below:

Sample Stability Chart for Chemistry Analytes

Day(s) and Time(s) Performed


Daily, 24 hours

Reference Values

284-300 mosmol/kg

Method Name

Freezing Point Depression

CPT Code Information


LOINC Code Information