Osmolality, Urine
Also known as: Urine Osmolality
Use
Evaluate concentrating ability of the kidneys (eg, in acute and chronic renal failure); evaluate electrolyte and water balance; used in work-up for renal disease, syndrome of inappropriate antidiuretic hormone secretion (SIADH), and diabetes insipidus; may be used with urinalysis when patient has had radiopaque substances, has glycosuria or proteinuria;1 evaluate dehydration, amyloidosis. Osmolality is desirable in examination of neonatal urine when protein or glucose are present.2
Special Instructions
If 24-hour urine is collected, record total urine volume on the request form. Centrifuge urine sample after collection for five minutes at 4°C to 25°C to remove gross particulate matter. Refrigerate the specimen for storage.
Limitations
This test has not been validated for measuring osmolality of fetal urine. Simultaneous determination of urine and serum osmolalities assists interpretation. Ratio differences in urine to plasma levels help in determining concentrating ability.
Methodology
Automated Analyzer (Clinical Chemistry)
Biomarkers
LOINC Codes
- 2695-5
- 2695-5
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
2 mL
Minimum Volume
0.2 mL
Container
Plastic urine container, no preservative
Collection Instructions
Centrifuge urine sample after collection for five minutes at 4°C to 25°C to remove gross particulate matter.
Storage Instructions
Refrigerate.
Causes for Rejection
Fetal urine sample received
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |