Urinalysis Flashcards
Diuresis
increased urine production due to a non pathologic process
polyuria
increased urine production due to a pathologic process
oliguria
decreased urine production given the degree of hydration
pathologic: dehydration, fever, acute kidney injury
non-pathologic: increased ambient temperature and panting
anuria
minimal to no production
pollakiuria
increased frequency of urination with normal urinary volume
what artifacts are associated with delayed urinalysis?
- formation of crystals
- bacti growth
- cell degeneration
- increased pH
- Decreased bilirubin and urobilinogen
- increased USG
- Equine urine can turn red/brown with storage
what are the different collection methods for urinalysis?
- Free catch
- Catheterization
- Cystocentesis
Pros and Cons of Free Catch
Pros: owner can obtain sample and there is not risk of trauma
Cons:
- likely contamination with cells and bacteria
- kidneys, ureters, bladder, genital tract, external skin
- depends on animals willingness to provide sample
Pros and Cons of Catheterization
Pros:
- minimizes external contamination
- sample obtained immediately
- relieve obstruction
Cons:
- difficult in females
- increases number of squamous epithelial cells
- possible catheter-induced hematuria
Cystocentesis Pros and Cons
Pros:
- least amount of contamination
- sample obtained immediately
- can relieve bladder distension
Cons:
- requires cooperative animal/sedation
- Iatrogenic blood contamination
- risk of bladder laceration/rupture or enterocentesis
- risk of tumor seeding
what is the impact of bacteria on urine test results?
- contamination
- bacterial urease breaks urea down to ammonia -> will increase urine pH
what is the difference between urine dipstick protein and SSA test?
Urine dipstick: can be performed on unspun urine or on the supernatant post-centrifugation. Analyzes the amount/value of pH, Glucose, Ketones, Blood, Bilirubin, Protein
Protein via SSA: used to confirm proteinuria in alkaline samples. It is better than dipstick at detecting Bence-Jones proteins, but can still have false -
Both are more sensitive for albumin than other proteins
red urine color
RBC, hemoglobin, myoglobin
red-brown urine
RBC, hemoglobin, myoglobin, methemoglobin
Brown-black urine
methemoglobin from hemoglobin or myoglobin
yellow - orange urine
bilirubin
yellow-green or yellow-brown urine
bilirubin and biliverdin
prolonged storage or urine in snow in horses can discolor urine to __
red-brown
what are the causes for RBC lysis in urine?
Bilirubinemia
what is the relationship between urine volume and USG?
in general, USG and urine volume have an inversely proportional relationship
low urine volume = high USG
high urine volume = low USG
what artifacts cause refractometer USG errors?
the refractometer must be temperature - calibrated
- USG values from a human refractometer will be very similar to the values from a veterinary refractometer in dogs and large animals but will overestimate the USG in cats
- Turbid samples may make the line difficult to read
- interferences: false increases with marked proteinuria or glucosuria
causes of increased bilirubin in urine
- dogs with concentrated urine (>1.025) can have trace to 1+
- Bilirubinemia: hemolysis and hepatoniliary disease
causes of increased glucose in urine
normal urine should not contain glucose
- hyperglycemia-persisten (DM)>transient (stress)
- Fanconi syndrome - proximal tubular defect
- some antibiotics (amoxicillin, gentamycin) - tubular damage
causes of increased ketones in urine
ketones should not be present in the urine of healthy animals
Diabetes mellitus
Negative energy balance caused by anorexia, starvation, bovine ketosis, pregnancy toxemia
How to interpret changes in the UPC ratio?
UPC ratio is used to detect glomerular or tubular disease and should not be used on post or pre-renal proteinuria
Normal < 0.2
Borderline 0.2-0.5
Renal proteinuria 0.5-1.0
do not use this metric if there is active urine sediment, hemoglobinuria, myoglobinuria
glomerular proteinuria
- primarily albumin
- UPC>3
- may lead to hypoalbuminemia (PLN)
tubular proteinuria
- LMW proteins
- UPC 0.5-3
- will not lead to hypoalbuminemia
UPC is helpful to differentiate glomerular from tubular disease when __
we know the proteinuria is renal
laboratory data with nephrotic syndrome
proteinuria
hypoalbuminemia
hypercholesterolemia
edema
what crystals when seen in relatively low numbers are normal?
- Amorphous
- magnesium ammonium phosphate (struvite)
- calcium oxalate dihydrate
Amorphous Crystals
small, irregularly shaped crystals
variable composition
seen in healthy patients
magnesium ammonium phosphate (struvite) crystals
can be seen in healthy dogs, cats, and ruminants
also seen with bacterial-induced alkalinuria
calcium oxalate dihydrate crystals
colorless octahedrons or envelopes
can be seen in healthy animals, with hypercalciuria or hyperoxaluria
can develop with prolonged sample storage
Bilirubin Crystals
yellow to red-orange, needle like to granular crystals
indicates bilirubinemia
can be seen in healthy dogs
abnormal in other species
calcium carbonate crystals
colorless to yellow, spherical with radial striations, oval, or dumb bell shapes
normal in horses and guinea pigs
not seen in dogs, cats, and ruminants
ammonium biurate crystals
brown, spherical with irregular projections “thorn apple”
common in dalmations and english bulldogs
in other dog breeds or cats they suggest liver dysfunction and portosytemic shunting
less common crystals
calcium oxalate monohydrate
cystine
with casts (cyllindruria) low numbers are __ while increased numbers indicate ____
normal, renal tubular damage
hyaline casts
protein
granular to waxy casts
different stages of cellular cast degeneration
