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Mayo Clinic Laboratories

Test Code ROSM Osmolaity, Urine

Specimen and Container/Tube

Specimen Type: Urine, Random Collection

Preferred Specimen: Sterile Plastic Container

Other Acceptable specimens: Sterile Clean Glass Container

Specimen Stability

Storage Temperature

Stability

Room temperature

8 hours

Refrigerated

7 days

Frozen

Not Applicable

Collection Instructions

  • Collect specimen per standard laboratory collection procedures. 
  • No preservatives or additives.

 

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

  • Collect specimen per standard collection procedure and send to laboratory immediately. 
  • No preservatives or additives.

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • No preservatives or additives
  • Aliquot urine into plastic tube containing a minimum of 0.2 mL of specimen.
  • Urine samples must then be sent refrigerated at 2-8oC.

 

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are collected with preservatives or additives.
  • Specimens that have been stored at room temperature for extended periods (>8 hours).

Reference Values

 

Test

Age

Sex

Reference Range

Osmolality, Urine

All

All

500 - 800 mOsm/kg

Critical Values

Not applicable

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: 1 hour 

Routine Turnaround Time: 4 hours 

Testing Schedule:  24/7

Clinical Indications

Useful in evaluating increased and decreased urine output. Serum osmolality is often useful to interpret urine osmolality.

Test Components

Osmolality, Urine

Methodology

Freezing Point Depression, Osmometry

CPT Codes

83935

LOINC Codes

TBD

Additional Information

​​​​​​Not applicable 

Last Review Date

6/4/25

Volume

Preferred Volume: 2.0 mL

Minimum Volume: 0.5 mL