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HelpTest ID SGU Specific Gravity, Urine
Useful For
As a partial assessment of the kidney’s ability to concentrate urine
Method Name
Refractometer
Reporting Name
Specific GravitySpecimen Type
UrineContainer/Tube: 16x100 mm polypropylene tube
Specimen Volume: 5 mL
Collection Instructions:
1. Collect a random urine specimen.
2. Keep specimen frozen.
Specimen Minimum Volume
1 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Urine | Frozen (preferred) | 7 days |
| Refrigerated | 7 days |
Clinical Information
Specific gravity (SG), the ratio of the mass of a solution compared to the mass of an equal volume of water, is an estimate of the concentration of substances dissolved in the solution.
Urine SG can be used to assess the kidney’s ability to concentrate or dilute urine. However, because protein, glucose, and contrast dye have molecular masses that are relatively large compared to other major components of urine (eg, sodium, chloride, potassium), they disproportionately affect SG. In these cases, urine osmolality is a better measure of urine concentration.
Reference Values
1.002-1.030
Cautions
Urine with contrast dye, glucose, or excessive protein should not be evaluated with this test.
Urine osmolality is a better measure of urine concentration.
Day(s) Performed
Monday through Sunday; Continuously
Report Available
Same day/1 dayPerforming Laboratory
Mayo Medical Laboratories in Rochester
CPT Code Information
81003