Urinalysis Flashcards
What is the best sample for Urinalysis?
- Sterile (cystocentesis) if for culture & sensitivity
- Best results - analyze within 30 min
- Delayed - refrigerate & protect from light
- warm to room temp for analysis
- consistent volume
What do the different urine colors indicate?
- Colorless - dilute
- Light yellow - normal
- Dark yellow - normal or concentrated (urochromes, flavins)
- Red - hemoglobinuria, myoglobinuria, hematuria
- Orange/brown - bilirubin
- Coffee-brown - Myoglobinuria, Methemoglobinuria
What are the different transparencies of urine indicative of?
- Clear: healthy (most animals)
- Hazy to Cloudy: crystals, cells, mucus, bacteria, casts, spermatozoa, or other material
- Horses normally have cloudy urine
Why is horse urine normally cloudy?
mucoproteins in urine produced by renal epithelial cells
What does the Urine dip-stick reliably test for?
- Protein
- Glucose
- Ketones
- pH
- Bilirubin
- Hemoprotein (blood)
What is the Urine Dip-stick test unreliable for?
- Urobilinogen - product of bacterial degradation of bilirubin in the gut
- Nitrite - screen for bacteruria in humans, not animals
- Leukocyte esterase - polyuria in people, not animals
- Specific gravity
What determines Urine pH?
- In Health - primarily by diet
- increased protein catabolism = more acidic urine
- 6 - 7.5 in dogs/cats
- decreased protein catabolism = more alkaline urine
- 7.5-8.5 in equids/ruminants
- increased protein catabolism = more acidic urine
- Changes occur in response to systemic A/B disorders
- but urine pH is NOT an accurate indicator of A/B balance
- Infection with urease-producing bacteria results in alkalinization of the urine
What Urine protein does the Dip-stick test for?
- Measures albumin best
- Also sensitive to hemoglobin & myoglobin
- Does NOT detect Bence-Jones proteins
- Very alkaline urine OR contamination by some cleaning agents will cause a false positive
What rule outs have to be done before attributing proteinuria to renal disease?
- Prerenal (overload) proteinuria
- hemoglobinuria
- myoglobinuria
- Postrenal proteinuria
- hemorrhage into the genitourinary tract
- inflammation, trauma, neoplasia
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Should there be glucose in urine?
- Glucose is freely filtered in the glomerulus - no barrier to entry of glucose into the tubular filtrate
- Glucose is efficiently reabsorbed in the proximal tubule
- NO glucose should be in urine
- Glucosuria is present if the renal threshold is exceeded
What are the different renal thresholds for glucose in different species?
- Dogs - 180mg/dL
- Cats - 280
- Horse - 160
- Cattle - 100
How are false positives/negatives for urine glucose acheived?
- False positive - contamination with cleaning agents
- False decreases/negative:
- Vit C
- Presence of ketones
- Sensitivity of test decreased with cold urine
What is Hyperglycemic glucosuria?
- Most common cause of glucosuria
- Hyperglycemia caused by:
- Diabetes mellitus - lack of insulin
- Severe pancreatitis
- Hyperadrenocorticism - insulin resistance due to increased cortisol secretion
- Severe stress/excitement - insulin resistance due to catecholamine release
- Iatrogenic - admin of glucose containing fluids
What are other interpretations of Glucosuria?
- Hyperglycemic glucosuria
- Normoglycemic glucosuria
- previous, transient episode of hyperglycemia
- Renal tubular defect
- Acquired - damage to tubular epithelium
- eg - gentamycin tox
- Inherited - Canine Fanconi-like syndrome
- Basenji & labs
- Acquired - damage to tubular epithelium
What Ketones is the Urine Dip-stick testing ro?
- Acetone, Acetoacetate & B-hydroxybutyrate are the ketones
- test only detects acetone & acetoacetate
- B-hydroxybutyrate is produced in the largest quantity though
- Ketones are NOT present in healthy urine
- False positives can occur with pigmented urine
- Ketonuria indicates a systemic problem - precedes detectable ketonemia