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Specific Gravity, Body Fluid
Test CodeBFSG
Alias/See Also
Epic: LAB199
Preferred Specimen
Specimen Type: Body fluid
Sources: Peritoneal fluid (peritoneal, abdominal, ascites, paracentesis), Pleural fluid (pleural, chest, thoracentesis), Drain fluid (drainage, JP drain), Pericardial
Collection Container: Sterile container
Specimen Volume: 5 mL
Minimum Volume
1 mL
Instructions
- Keep specimen refrigerated.
- Specimens should be tested within 24 hours.
Transport Container
Clear top (no additive) tube
Specimen Stability
Room temperature: Unaccpetable
Refrigerated: 24 hours
Frozen: Not defined
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Unlabeled, mislabeled, wrong tube type, hemolyzed, QNS, exceeds specimen stability requirements.
Methodology
Refractometer
Setup Schedule
Daily
Report Available
Same day
Reference Range
<1.036
Clinical Significance
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.
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.
Performing Laboratory
Inova Laboratories
2832 Juniper Street
Fairfax, VA 22031
Last Updated: May 8, 2023
Last Review: N. Wolford, May 8, 2023