Contributors: Kathleen P Freeman, Karen L Gerber
Species: Feline | Classification: Lab Tests
- Changes in chemical and physical characteristics of urine occur in urinary tract and systemic disease and trauma.
- Such changes can be detected by the reaction of specific components with reagents impregnated in dipstick pads which produce characteristically graded color changes.
- Results are qualitative and depend on subjective interpretation of user.
- Monitoring glucose control treatment of diabetes mellitus Diabetes mellitus (crude method).
In combinationA screening test for any ill animal as a preliminary to full urinalysis and hematology.
- With other laboratory tests for investigation of polyuria/polydipsia.
- Serum creatinine Blood biochemistry: creatinine and urine specific gravity (refractometer) Urinalysis: specific gravity to assess renal function.
- Serum bile acids Blood biochemistry: bile acid and serum urea Blood biochemistry: urea to investigate hepatic encephalopathy Hepatic encephalopathy due to portocaval shunt Congenital portosystemic shunt (CPSS).
- Serum glucose Blood biochemistry: glucose to confirm diabetes mellitus.
- Culture and sensitivity Urinalysis: culture and sensitivity to investigate upper and lower urinary tract infection Cystitis: bacterial.
- Ultrasonography Ultrasonography: bladder and urinary tract to investigate hematuria.
- Hematology Hematology: complete blood count (CBC) in severe hemolytic disease.
- Hematology and biochemistry to investigate endocrinopathy.
- Refractometer method Urinalysis: specific gravity preferred for specific gravity measurement.
Source of Test Material
Quantity of Test Material
- Standard volume of 4-5 ml preferred.
- Trauma during collection may contaminate sample.
- Delay between collection and analysis → less reliable results.
- Sample standing for >30 minutes must be refrigerated (2-8°C).
- Urine must be at room temperature before analysis.
- Protect sample from bright light.
Timing of test
- The composition of urine varies throughout the day.
- Sample for screening test at any time of day.
- Urine can be refrigerated at 2-8°C for a few hours (maximum 12 hours).
- If sample is to be stored, divide into two containers, add preservative (boric acid tablet or 10% formalin) to one and refrigerate both.
- The sample with preservative is for sediment examination. The sample with no preservative is for dipstick (chemical) analysis.
- Specimen for bacteriologic culture should be in sterile container without preservative.
- Standard mailing times.
- Package according to mailing regulations Transportation of diagnostic specimen.
- Rapid, complete immersion of the dipstick with immediate shaking off of excess urine as well as holding the dipstick level is needed to avoid run-off between pads.
- Compare the color change of dipstick to the reference range at the correct time specified on product.
- Determine specific gravity by refractometer.
Dipstick specific gravity does not correlate well with refractometry.
- Can be performed in-house.
- All external laboratories.
- Low to high.
- Low to moderate.
Technique (Intrinsic) Limitations
- ?Reliable reading of specific gravity of urine.
Technician (Extrinsic) Limitations
- Interpretation of color change is subjective, so routine use of the same technician/vet will result in more consistent results.
Normal (Reference) Values
- Usually acid, mean 6.0, range 5.0-9.0.
Vegetable and cereal diets can result in alkaline urine.
- If specific gravity >1.020: trace.
- Negative (unreliable in animals for screening for bacteria because of large number of false negative tests).
Errors and Artifacts
- Not using fresh urine.
- Incorrect storage of dipstick
- Urine not at room temperature.
- Reading dipstick at incorrect time.
- Using a collection technique other than cystocentesis.
- Inconsistent technique.
- Dipstick too old (past expiry date).
- Increase: sample standing open at room temperature for few hours (loss of CO2), furosemide Furosemide at therapeutic dose, contamination with urease-producing bacteria (distal urinary tract or environment), detergents or disinfecting agents in collecting containers.
- Decrease: ammonium chloride Ammonium chloride, ascorbic acid Vitamin C.
- False positive: chlorhexidine Chlorhexidine or other quaternary ammonium compounds, presence of urease-producing bacteria, prolonged immersion of dipstick ( → loss of buffer), administration of alkalinizing drugs.
- False negative: failure to detect Bence-Jones proteins (associated with myeloma), acidification of urine following collection.
- Increase: intravenous fluids containing dextrose, aminoglycoside toxicity.
- Decrease: refrigerated urine, large amounts of ascorbic acid Vitamin C, tetracycline Tetracycline (ascorbic acid in formulation), salicylates Acetyl salicylic acid, ketones, low urine pH, bacteria.
- Increase: large amounts of phenothiazines Acepromazine maleate.
- Decrease: ascorbic acid, aspirin Acetyl salicylic acid, prolonged exposure to ultraviolet light.
- False positives common - often indicate strips are out of date or have been stored incorrectly.
- Increase: trauma during sampling, contamination with vaginal/preputial secretion.
- Decrease: hemolysis occurs in hyposthenuric, very acid urine, very alkaline urine.
Must interpret with urine sediment examination.
- Increase: phenazopyridine.
- Decrease: frequent voiding, ascorbic acid Vitamin C.
- 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 & Mahaffey E A (1994) Veterinary Laboratory Medicine Clinical Pathology. 3rd edn. Iowa University Press, USA.