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HelpOrder Code OSM24 Osmolality, 24 Hour, Urine
Necessary Information
24-Hour volume (in milliliters) is required.
Specimen Required
Supplies:
-Diazolidinyl Urea (Germall), 5.0 mL (T822)
-Urine Tubes, 10 mL (T068)
Container/Tube: 24-hour graduated urine container with no metal cap or glued insert
Specimen Volume: 10 mL
Collection Instructions:
1. Collect urine for 24 hours
2. Add 5 mL of diazolidinyl urea as preservative at start of collection or refrigerate specimen during and after collection.
Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.
Useful For
Assessing the concentrating and diluting ability of the kidney using a 24-hour urine collection
Method Name
Freezing Point Depression
Reporting Name
Osmolality, 24 HR, USpecimen Type
UrineSpecimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Refrigerated (preferred) | 14 days |
| Frozen | 14 days | |
| Ambient | 72 hours |
Reject Due To
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.Reference Values
0-11 months: 50-750 mOsm/kg
≥12 months: 150-1,150 mOsm/kg
Method Description
Measurement of the freezing point of urine is the most widely used principle in osmometers. The extent of lowering below 0° C (the freezing point of water) is a function of the concentration of substances dissolved in the urine. By definition, 1 milliosmole per kilogram lowers the freezing point 0.001858° C.(Schindler EI, Brown SM, Scott MG. Electrolytes and blood gases. In: Rifai N, Horwath AR, Wittwer CT, eds. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Elsevier; 2018:610-612)
Day(s) Performed
Monday through Sunday
Performing Laboratory
Mayo Clinic Laboratories in Rochester
CPT Code Information
83935