canis - Articles
Urinalysis: specific gravity
Overview
- Measure kidneys' ability to concentrate and dilute urine.
Uses
Alone
- Assessment of kidneys' ability to alter specific gravity of glomerular filtrate.
In combination
- With other tests of renal function in assessment of renal function.
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.
- Inaccurate for non-human urine/disregard for animal urine.
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.
- 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.
Other sources of information
- Kaneko J J (1997) Clinical Biochemistry of Domestic Animals. 5th edn. Eds: Harvey J W & Bruss M L. Academic Press, USA.
- Duncan J R, Prasse K W & Mahaffy E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, USA.