Urinalysis Flashcards
Dr. Swan
How much urine is required for a urine collection?
5 mL
What are the 3 ways of urine collection?
cystocentesis
free catch
catheterization
What are the pros and cons of free catch?
pros: non-invasive, no restraint
cons: not sterile, can be stressful, can cause injury
What are the pros and cons of catheterization?
pros: fairly sterile, can collect when there is little urine in the bladder
cons: epithelial cells can be elevated in sample, may require sedation, trauma or UTI
What are the pros and cons of cystocentesis?
pros: best for urine culture - sterile, no sedation
cons: bladder needs to be distended to palpate, can cause iatrogenic hemorrhage, low risk of perforation, can introduce metastasis
What are the physical properties of urine - color?
normal: yellow to amber
What are the physical properties of urine - clarity?
should be clear
cloudiness or turbidity indicates presence of formed elements such as
casts, cells, lipids, crystals, bacteria
Which species urines are naturally cloudy? Because of what?
equine and lagomorph
the presence of large amounts of mucus and/or calcium carbonate crystals
What are the physical properties of urine - specific gravity?
measure with refractometer
indication of tubular function - ability to dilute or concentrate urine
When do renal tubules lose their ability to concentrate urine?
66% loss
What should you always take into account when analyzing specific gravity?
the patient’s hydration status
What is hyposthenuria? Describe the tubular function. What are some diseases it affects?
when the USG is equal to or less than 1.008
still have tubular function (adding too much or not getting it out)
- nephrogenic diabetes insipidus
- central diabetes insipidus
What is nephrogenic diabetes insipidus? What does it cause?
tubules unresponsive to ADH
- hypercalcemia
- pyometra
- liver failure
- hypokalemia
What is central diabetes insipidus?
ADH deficiency
What is isosthenuria? Describe the tubular function.
urine USG is the same as serum USG which indicates there is enough tubular damage
the tubules can NEITHER concentrate nor dilute urine
What is the medullary concentration gradient established by?
BUN: 50%
Na+: 50%
What results in medullary washout?
decreases in BUN below reference interval
Na+ level less than 120 mmol/L
What is the chemical analysis of urine - pH?
measured on a reagent pad
What are the ideal pH of each species?
dog and cat: 6-7.5
horses and cattle: 7.5-8.5
What is the chemical analysis of urine - protein?
detects albumin
proteins are usually too big to pass glomerular barrier
dogs with adequately concentration USG are known to have negative trace to 1+ protein reactions in health
What is the chemical analysis of urine - 5 mechanisms of proteinuria?
pre-renal
glomerular
tubular
inflammation or hemorrhage
neoplasia
What is the chemical analysis of urine - protein 5 mechanisms - pre-renal?
mild proteinuria
overflow mostly commonly due to hypertension or exercise because increases blood flow to kidney and speed of filtration
What is the chemical analysis of urine - protein 5 mechanisms - glomerular?
generally profound proteinuria
concurrent hypoalbuminemia
3+, 4+
What is the chemical analysis of urine - protein 5 mechanisms - tubular?
occurs due to proximal tubular damage generally in acute renal diseases
rarely above a mild proteinuria or 1 to 2+ depending on USG
acute diseases can damage tubules
What is the chemical analysis of urine - protein - nephrotic syndrome?
clinical condition of protein losing nephropathy due to a glomerulopathy which describes:
proteineuria
hypoalbuminemia
ascites/edema
hypercholesterolemia
What is the chemical analysis of urine - protein - Bence Jones Proteinuria?
lymphoproliferative disease, commonly multiple myeloma
leishmaniasis
ehrlichiosis
babesiosis
NOT detected with reagent strip
What is the chemical analysis of urine - glucose?
proximal tubules should reabsorb back in
glucose concentrations exceed the renal threshold: glucosuria
What are the types of glucosuria?
transient
persistent
What is transient glucosuria?
ebbs and flows
corticosteroid stress
excitement
iatrogenic
What is persistent glucosuria?
diabetes mellitus (unmanaged)
falcon syndrome
renal tubular necrosis or ischemia
What is the chemical analysis of urine - ketones?
occurs with mobilization of proteins and formation of ketoacids which leads to ketone bodies in blood and urine - ketosis
3 major ketones produced
What are the 3 major ketones produced in ketosis? What is the most common, and what does the reagent strip detect?
B-hydroxybutyrate - most common
acetoacetate
acetone
2/3 ketones
What is the chemical analysis of urine - heme?
reagent strip detects 3 forms:
- hemoglobin
- methemoglobin
- myoglobin
speckled appearance because erythrocytes lysed
Describe how you can differentiate between hemoglobin, myoglobin, and methemoglobin when chemically analyzing.
hemoglobin/myoglobin: does not sediment out; the supernatant will remain pink-tinged
methemoglonin: brown color
myoglobin: results from breakdown in muscle so creatinine kinase (CK) should be elevated
What is the chemical analysis of urine - bilirubin?
not expected to be in urine except in dogs
detected bilirubin is conjugated
What are some false positives of glucose regarding reagent tests?
hydrogen peroxide
bleach
What are the steps to urinalysis?
What is the sediment exam - erythrocytes?
reported as a mean # or range per 400x HPF
hematuria: increased erythrocyte # per HPF in urine
What are some causes of hematuria?
pathologic: vascular damage, thrombocytopenia or thrombocytopathia, coagulopathies
iatrogenic
What is a sediment exam - leukocytes?
reported as a mean # or range per 400x HPF (fever than 5 per HPF may be fine)
round, colorless cells with a grainy texture
pyuria
What does this show?
hematuria
What does this show?
bactiuria
What are some causes of pyuria?
infectious: bacteria, fungi, parasites
non-infectious: neoplasia, urolithiasis, necrosis
What is a sediment exam - bacteria?
should see white blood cells (pyuria)
should not be there in a healthy animal
What is a sediment exam - other organisms?
rare
yeast, prototheca, eggs/oocysts, spterm
What is a sediment exam - epithelial cells?
expected in the urine
What are the types of epithelial cells in the urine?
tubular cells: uncommon, cuboidal to round, may be present in cohesive clumps
urothelial: round
inflammatory, hyperplastic, or neoplastic processes can increase the number of epithelial cells within a sample
What is a sediment exam - casts?
cylindrical concretions with round, square, or tapered ends that mirror the tubular segments from which they are formed
mucoproteins +/- lipids or cells
low numbers usually present in health
What can the presence of casts in the urine indicate?
acute injury - indication of tubular disease
What are the types of casts?
hyaline casts
epithelial casts
lipid casts
granular casts
leukocyte casts
hemoglobin or myoglobin casts
waxy casts
What is this?
urothelial cells - (epithelial cell)
What is a sediment exam - crystals?
formed because of precipitation of different kinds of salts
pH influences whether certain types of crystals will precipitate
T/F: Crystalluria is a risk factor for urolithiasis and is a reliable indicator of urolithiasis
FALSE - is not!
lots of blocked cats are because of dried solidified blood
What are the radiopaque crystals you can observe?
struvite
calcium carbonate
calcium oxalate dehydrate
calcium oxalate monohydrate
calcium phosphate
so, lots of calcium structures - can form uroliths
What are urolith forming but not necessarily can be detected by radiograph?
uric acid
cystine
then struvite and the calciums
“I can’t s(Cy)ee yoU”
What is struvite and what does it look like? Is it radiopaque or radiolucent?
colorless, 3D, look like coffins
most common in dogs and cats
any pH
radiopaque
What does a sediment exam - crystals - bilirubin look like?
needle-like to granular yellow crystals
form from conjugated bilirubin often in association with cells
no clinical significance in canine urine
acidic
What is calcium carbonate and what does it look like? Is it radiopaque or radiolucent?
large spheres with radial striations which are colorless to yellow brown
normal in horses, rabbits, guinea pigs, and goats
alkaline
radiopaque
What is calcium oxalate dehydrate and what does it look like? Is it radiopaque or radiolucent?
colorless squares whose corners connect via intersecting lines, aka “envelope” appearance which are birefringent with polarizing light
radiopaque
What is calcium oxalate monohydrate and what does it look like? Is it radiopaque or radiolucent?
spindle, oval, hemp seed, dumbbell, or picket fence
picket fence: ethylene glycol intoxication in dogs and cats
radiopaque
What is ammonium biurate and what does it look like? Is it radiopaque or radiolucent?
“thorn apple”
common in dogs and cats with acquired or congenital portosystemic shunts or hepatic dysfunction
What is uric acid and what does it look like? Is it radiopaque or radiolucent?
yellow to yellow-brown retractile diamonds or rhomboidal plates
hepatic dysfunction because in liver: uric acid —> urea nitrogen
radiolucent
What are cystine crystals and what do they look like? Is it radiopaque or radiolucent?
results from defective tubular resorption of certain amino acids
sex-linked
neutral to acidic
radiolucent
What are calcium phosphate crystals and what do they look like? Is it radiopaque or radiolucent?
colorless needles or plates
rare in SA
associated with conditions promoting hypercalcemia
- hyperparathyroidism
- hyperadrenocorticism
- distal renal tubular acidosis
What are amorphous and what does it look like?
non-specific term indicating small crystals which are not identifiable as to the source
appear as aggregates of finely granular material.
What are drug-associated crystals and what do they look like? Is it radiopaque or radiolucent?
sulfa drugs
lignin test
need clinical history
What crystal?
cystine
What crystal?
calcium oxalate monohydrate
What crystal?
ammonium biurate
Struvite or calcium oxalate dehydrate?
calcium oxalate dehydrate “envelope”
What crystal?
calcium phosphate
What crystal?
calcium carbonate
What crystal?
bilirubin
What crystal?
uric acid
What crystal?
struvite
What crystal?
amorphous
What crystal?
drug-associated
What is the Urine Protein to Creatinine Ratio (UPC)?
performed in patients with an excessive proteinuria
measures the protein relative to the amount of creatinine in urine
What is the SSA test?
sulfosalicylic acid precipitation test - add this to the urine
causes acidification of urine to increase turbidity
detects both albumin and globulins
useful with suspicion of multiple myeloma and bence-jones proteins
