Felis ISSN 2398-2950
Urinalysis: specific gravity
Synonym(s): SG
Contributor(s): Kathleen P Freeman, Karen L Gerber, Andy Torrance
Overview
- Measure kidneys' ability to concentrate and dilute urine.
Sampling
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Tests
Methodologies
Refractometer (most common)
- Single drop placed on glass surface; reading relative to specific gravity of distilled water (= 1).
Urinometer
- Need large volume (15-45 ml) but can dilute and recalculate specific gravity reading.
- Three-quarter fill cylinder then insert urinometer and read scale at interface of air with urine; the scale reading represents the 2nd and 3rd decimal placing, eg reading of 25 = 1.025.
Dipstick
- Results do not correlate well with refractometer.
Availability
- Standard practice laboratory technique.
Technique (intrinsic) limitations
- Cannot interpret results in isolation from other urinalysis results and lab tests.
- Single random result outside normal reference range cannot establish diagnosis.
Result Data
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Further Reading
Publications
Refereed papers
- Recent references from VetMedResource and PubMed.
- Watson A D (1998) Urine specific gravity in practice. Aust Vet J 76(6), 392-398.
- Buffington C A et al(1997) Clinical evaluation of cats with non-obstructive urinary tract diseases. JAVMA 210(1), 46-50.
- Brobst D (1989) Urinalysis and associated laboratory procedures. Vet Clin North Am Small Anim Pract 19(5), 929-949.
- McCaw D L, Fleming E J & Mikiciuk M G (1989) Interpreting the results of urinalysis - a key to diagnosing renal disorders. Vet Med 84(3), 281-286.
- Barsanti J A et al (1980) Laboratory findings in urinary tract infections. Vet Clin North Am Small Anim Pract 9(4), 729-748.
Other sources of information
- Kaneko J J (1997) Clinical Biochemistry of Domestic Animals. 5th edn. Harvey J W & Bruss M L (eds). Academic Press, Boston.
- Duncan J R, Prasse K W & Mahaffy E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, Ames, Iowa.