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HelpTest Code LAB420 Urine Osmolality
Clinical System Name
Urine Osmolality
Synonyms
OSMO U
Osmolality Urine
LAB420
Sample Requirements
Specimen: Random urine
Container(s): Sterile Screw-Capped Container
Preferred Vol: 0.5 mL
Minimum Vol: 0.1 mL
Processing Instructions
Deliver sample to Core Chemistry.
Reject due to: Non-sterile container, insufficient quantity, incorrect storage temperature, age of specimen
Spin: Y
Aliquot: Y
Storage location: Core Chemistry Refrigerator
Off-site collection: Sample MUST be at room temperature before centrifuging. Centrifuge urine to remove particulate matter which could accelerate crystallization. Spin urine and transfer supernate to plastic tube and refrigerate or freeze.
Stability
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | RT | ≤ 4 h |
| Urine | 2-8 C | ≤ 24 h |
| Urine | -20 C or - 70 C | ≤ 30 d |
Availability
| STAT | Performed | TAT |
|---|---|---|
| Y | 24/7 | 1 h |
Performing Laboratory
Seattle Children's Laboratory
Department
Department: Core Chemistry
Phone Number: 206-987-2617 (Client Services)
CPT Codes
83935
Methodology
Method: Freezing Point Depression by Fiske Micro-Osmometer Model 210
Analytical Volume: 0.06 mL
Reference Range
| Age | mOsm/kg |
| < 1 year | 50 - 600 |
| 1 year - Adult | 50 - 1400 |
The urine osmolality output varies greatly with diet. Normal urine osmolality can be as much as 1400mOsm with maximal ADH stimulation, and as little as 50 with maximal ADH suppression. Thus, urine osmolality should be interpreted in light of what is known about the patient's hydration status and plasma osmolality.
Description
Urine osmolality, a measure of urine concentration, is used to help evaluate the body’s water balance. It is typically monitored to evaluate renal function, sodium balance, polyuria, and oliguria.