Urinalysis Flashcards
T/F cystocentesis is an invasive procedure
true
when is a cysto contraindicated
Local pyoderma, coagulopathy, neoplasia (risk of seeding)
Insufficient volume of urine in the urinary bladder
Patient resists restraint and abdominal palpation
what is the recommended technique for urine culture
Cystocentesis
Voided urine
mid stream flow
generally acceptable for U/A, sediment exam
not suitable for culture
Catheterization can result in
Blood or epithelial cell contamination
Trauma
Technically difficult, especially in females
Track materials into bladder and cause bladder infection
Perform re-check UA to check for UTI after catheterization
urine should ideally be evaluated within
30 min
– Refrigerate
– Low USG can lead to cellar lysis – analyze soon!
how long can you refrigerate urine for
up to 12 h in sterile, opaque, airtight container
– Warm to room temp for 20 min
– Gently swish to remix and resuspend sediment
T/F exposure to light can turn urine a darker yellow
true
yellow-orange urine
bilirubin
yellow-green/yellow-brown urine
bilirubin and biliverdin
red urine
RBCs, HgB, and MgB
red-brown urine
RBCs, Hb, Mgb, MetHgb
brown to black urine
MetHgB
how to differentiate to between RBCs, Hb, Mgb, and MetHgb
– Hemoglobin: serum will also be red/pink
– Myoglobin: doesn’t accumulate in serum,
– MetHgb: serum is brown/black serum will not be discolored
– RBCs will settle to the bottom after centrifugation
miscellaneous color changes
Drugs - especially drugs with dyes
Horse urine with storage or on snow can turn reddish
– this is not evidence of hematuria
clarity:
Clear -> slightly cloudy -> cloudy -> opaque -> flocculent (chunky)
T/F horses tend to have turbid/ cloudy urine
true: contains mucous (looks like beer-think budwiser clydesdales)
what is cloudiness or turbidity caused by
– “formed elements”
– Cells, crystals, bacteria, casts, and lipid droplets (some lipid normal in cats)
read the SpGr off of the
supernatant
why is it important to use room temp urine for SpGrq
Cold fluids are more dense, FALSELY increases SpGr
what do you interpret USG with
- Serum [BUN] & [CREA]
- Amount of urine
- Hydration status
T/F each species has a normal USG value
False: there is no “normal” USG; indicative of adequate [ ] ability
- Dog >1.030
- Cat >1.035
- Horse & Cattle >1.025
what are the “big 6” on a dipstick
glucose
bilirubin
ketones
blood
pH
protein
T/F glucose can be present in urine in health puppies
true
T/F cold urine falsely elevates glucose
false: decreases it
renal threshold for dogs -glucose
180 mg/dL
renal threshold for cats - glucose
280 mg/dL
renal threshold for horses - glucose
180 mg/dL
renal threshold for cattle - glucose
100 mg/dL
5 main causes of hyperglycemic glucosuria
Diabetes mellitus – glucose
Hyperadrenocorticism – cortisol
Drugs – dextrose, glucocorticoids, progesterone
Postprandial (P just ate)
Acute pancreatitis
3 main causes of normoglycemic glucosuria
Transient stress
Reversible tubular damage: drugs, hypoxia, infection, toxins
Cats with urethral obstruction
T/F more than 20% of normal dogs have 1+ bilirubin
true:
– Has low renal threshold
– Canine PCT can conjugate Hgb & excrete bilirubin
T/F Expect bilirubinuria before bilirubinemia
true:
– 2+ bilirubin & USG 1.020 – more concerned
– 2+ bilirubin & USG 1.040 – less concerned
in any species other than dogs bilirubinuria is
ABNORMAL
bilirubinuria can be indicative of
liver disease
bile duct onstruction
hemolysis
what causes false negatives [bilirubin}
Old sample
Light exposure
Nitrites
Ascorbic acid
what are they true ketones
acetoacetic acid and acetone
T/F ketones are present in normal animals
False
Question, what kind of bear is best?
black bear
Fact, bears eat beets
Bears, beets, “Battlestar Galactica.”
which ketones are detected on dipstick
Acetoacetic acid & acetone – NOT β-hydroxybuterate
what it the predominant form of ketones in ruminants
β-hydroxybuterate
– Expect β-OHB in bovine ketosis & pregnancy toxemia in ewes
when do you get ketonuria
Negative energy balance
DKA
Insulinoma
what can blood on the dipstick indicate
Hgb, Mgb or RBCs
– RBCs lyse & release Hb
– Bleach causes a F(+) reaction
if blood on the dipstick is due to hematuria:
Clears with centrifugation
Speckled pattern if low-grade
causes of hematuria
Trauma, infection, inflammation, infarction, calculi, neoplasia, coagulopathy
if blood on the dipstick is due to hemoglobinuria
- Urine supernatant NOT clear after centrifugation
– still red colored - No RBCs found in sediment
causes of hemoglobinuria
intravascular hemolysis
– Serum will be pink/red
– Patient will be anemic
T/F myoglobinemia is visible
false
what leads to the release of myoglobin
Myocyte damage
– ↑ AST & CK – muscle-origin on biochemical profile
– Urine supernatant red
normal urine pH of Dogs and Cats
6.5 – 7.5 * carnivores/omnivores
normal urine pH of Horses and Cattle
7.5 – 8.5 * herbivores
renal tubular dysfunction leads to…
paradoxically alkaline urine
alkaline pH caused by
Urinary Tract Infections (UTI) - urea splitting bacteria
Low protein diets
Respiratory alkalosis, Metabolic alkalosis
Alkalinizing drugs
what hinders interpretation of urine pH
pigmenturia
examples of urea splitting bacteria
Proteus
Pseudomonas
Staphylococcus
causes of acidic pH
High protein diets: Carnivores/omnivores; herbivores on milk
Respiratory and Metabolic Acidoses
Hypochloremic metabolic alkalosis + severe dehydration
Hypokalemia (K/H exchanger)
Furosemide
which protein is primarily detected on dipstick
albumin
which proteins is the dipstick insensitive to
Bence Jones proteins
Globulins
causes of proteinuria
‒ Pre-renal: Fever, hypertension, seizures, IV
‒ Renal: Glomerulonephritis, renal tubular injury
‒ Post-renal: Hemorrhage, infection
what should be ruled out with a positive protein reaction
hemorrhage (RBCs in sediment)
UTI/Cystitis (BacT and WBCs on sediment)
Intravascular hemolysis-hemoglobinurea (animal will be anemic)
proteinuria caused by renal disease
- Blood reaction will be negative (usually)
- Sediment will likely have casts
- Measure a UPCR
Proteinuria with nothing in the sediment is most often indicative of glomerular disease
T/F trace to 1+ protein is a normal finding in concentrated urine for dogs
true (remember 1+ bilirubin is also normal in dogs)
T/F proteinuria with dilute urine is a problem
true
Sulphosalicylic Acid Test (SSA)
Used to confirm dipstick protein results
Reacts with albumin, and also reacts adequately with globulins / Bence-Jones proteins
what does a discrepancy between SSA and dipstick indicate
there is protein other than albumin in the urine
See glob and BJ proteins with certain neoplasms- multiple myeloma and B cell tumors
urine sediment preparation
- Mix urine and transfer a standarized volume to a conical test tube
- Centrifuge at low speed for 5 minutes
- Decant urine without disrupting the sediment;
leave a small amount of urine for sediment resuspension
- Gently agitate the vial to resuspend the sediment
- Transfer a drop to a glass slide and place a coverslip
- Lower the condenser on your microscope
- Examine the entire coverslip, especially the edges
source of caudate cells
renal pelvis
renal cells
renal tubules
squamous epithelial cells
‒ Largest
‒ Thin
‒ Often transparent
‒ Angular or folded
significance of squamous epithelial cells
Seen in free catch urine
Rarely pathologic
transitional epithelial cells
‒ Round
‒ Vary in size
‒ Found individually or in clusters
significance of transitional epithelial cells
Seen with hyperplasia associated with inflammation
Seen in transitional cell tumors (benign and malignant)
caudate cells
cone-shaped
significance: pyelonephritis
renal cells
‒ Small
‒ Cuboidal to round
‒ Basal to central nuclei
‒ Found individually and in small groups or rows
‒ Seen with renal tubular injury: infectious, toxic, and ischemic injury
what are crenated RBCs
they are the pissed off cats of the RBC world- when urine has been stored or USG >1.025 (unhappy environment)
when do you see RBC lysis
USG
significance of RBCs in sediment
hemorrhage, inflammation
WBCs on sediment
1.5-2x larger than RBCs
Light gray, granular texture
Often visualize nucleus
Cannot easily differentiate in unstained preps
significance of WBCs
inflammation (infectious and noninfectious-stones)
when can you see start to see bacteria on sediment
‒ >10,000 rods/ mL
‒ >100,000 cocci/ mL
T/F air-dired wright stained is a better detector of bacteria
true
T/F there is no standard method for reporting bacteria
true
T/F bacteria spin down with centrifugation
false
other infectious agents include
dioctophyma renale
capillaria ovum
yeast and fungal hyphae (immunosuppressed)
- candida spp
Dirofilaria immitis
transitional cell carcinoma
Extremely difficult to diagnose and differentiate from inflammation- send it to a clinical pathologist!!!!
Normal transitional epithelial cells can be very variable in size
T/F free lipid droplets are common in cats
true
when can lipid presence have pathologic significance
renal tubular injury
Struvite crystals
Most common crystal in dogs and cats
Formation is favored in neutral to alkaline pH
significance of struvites
Can be found in clinical normal patients
Urease-positive bacteria promote formation (↑urine pH)
bilirubin crystals
Orange to copper granules
Usually present in small bundles
significance of bilirubin crystals
dogs: low number in highly concentrated urine is normal
Abnormal in all other species: ICTERUS
- r/o pre-hepatic - hemolysis (EVH)
- r/o hepatic/ post-hepatic - hepatobiliary disease
calcium carbonate
‒ Large spheres with radial striations
‒ Variably sized
‒ Colorless to yellow-brown (can cause brown-tinged urine in ↑↑↑ #s)
significance of calcium carbonate
NORMAL in horses, rabbits, guinea pigs, and goats
No reports in canine or feline urine.
calcium oxalate dihydrate
NORMAL in domestic animals
Storage artifact
Pathologic:
- Miniature Schnauzers are predisposed to calcium oxalate urolithiasis
- Increased calcium excretion due to hypercalcemia (e.g. hyperparathyroidism)
- Acute renal fialure
calcium oxalate monhydrate
Can be seen in healthy animals (esp horses)
Can be seen in animals with:
‒ Oxalate urolithiasis
‒ Hypercalciuric or hyperoxaluric disorders
‒ ETHYLENE GLYCOL TOXICOSIS (RARE)
