Urinalysis Flashcards
(38 cards)
1
Q
What is the best sample for Urinalysis?
A
- 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
2
Q
What do the different urine colors indicate?
A
- Colorless - dilute
- Light yellow - normal
- Dark yellow - normal or concentrated (urochromes, flavins)
- Red - hemoglobinuria, myoglobinuria, hematuria
- Orange/brown - bilirubin
- Coffee-brown - Myoglobinuria, Methemoglobinuria
3
Q
What are the different transparencies of urine indicative of?
A
- Clear: healthy (most animals)
- Hazy to Cloudy: crystals, cells, mucus, bacteria, casts, spermatozoa, or other material
- Horses normally have cloudy urine
4
Q
Why is horse urine normally cloudy?
A
mucoproteins in urine produced by renal epithelial cells
5
Q
What does the Urine dip-stick reliably test for?
A
- Protein
- Glucose
- Ketones
- pH
- Bilirubin
- Hemoprotein (blood)
6
Q
What is the Urine Dip-stick test unreliable for?
A
- 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
7
Q
What determines Urine pH?
A
- 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
8
Q
What Urine protein does the Dip-stick test for?
A
- 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
9
Q
What rule outs have to be done before attributing proteinuria to renal disease?
A
- Prerenal (overload) proteinuria
- hemoglobinuria
- myoglobinuria
- Postrenal proteinuria
- hemorrhage into the genitourinary tract
- inflammation, trauma, neoplasia
*
10
Q
Should there be glucose in urine?
A
- 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
11
Q
What are the different renal thresholds for glucose in different species?
A
- Dogs - 180mg/dL
- Cats - 280
- Horse - 160
- Cattle - 100
12
Q
How are false positives/negatives for urine glucose acheived?
A
- False positive - contamination with cleaning agents
- False decreases/negative:
- Vit C
- Presence of ketones
- Sensitivity of test decreased with cold urine
13
Q
What is Hyperglycemic glucosuria?
A
- 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
14
Q
What are other interpretations of Glucosuria?
A
- 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
15
Q
What Ketones is the Urine Dip-stick testing ro?
A
- 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
16
Q
What causes ketone bodies?
A
- Produced when there is a negative energy balance
- Starvation or inability to utilize carbohydrates (lake of insulin)
- Dogs/cats: diabetes mellitus
- Ruminants: metabolic disorders associated with lactation, late gestation
- Starvation or inability to utilize carbohydrates (lake of insulin)
17
Q
How sensitive is the Urine Dip-stick to blood?
A
- Very sensitive - positive with only 5-20 RBCs/uL
- Positives seen with:
- Hematuria - RBCs in urine
- Hemoglobinuria - free hemoglobin in urine
- Myoglobinuria - free myoglobin in urine
18
Q
How can one differentiate between Hematuria, hemoglobinuria, and myoglobinuria?
A
- Hematuria
- supernatant is not, or is only barely red
- RBCs in sediment
- Normal plasma color (clear)
- Hemoglobinuria
- Occurs due to intravascular hemolysis
- Red, clear supernatant
- Few or no RBCs in sediment
- Red plasma (hemoglobinemia)
- Evidence of anemia (hemolytic) on CBC
- Myoglobinuria
- Occurs due to muscle injury & necrosis
- Red-brown supernatant
- Few or no RBCs in sediment
- Plasma normal color (clear)
- increased CK and ASt
19
Q
What does the urine dipstick test for bilirubin tell a clinician?
A
- Bilirubin - produced from heme degradation (hemolytic disease or hepatobiliary disorders)
- Positive - conjugated bilirubin in urine
- Bilirubinuria may precede hyperbilirubinemia
- +1 reaction in concentrated urine is common in dogs
- Bilirubinuria in cats, horses and cattle is significant
- False decrease:
- bilirubin degrades with exposure to UV light
20
Q
What is the normal amount of RBCs and WBCs in urine sediment?
A
- RBCs < 5RBC/hpf (40x)
- WBCs <5WBC/hpf
- pyuria indicates inflammation
21
Q
What can all be found in urine sediment?
A
- RBCs
- WBCs
- Epithelial cells
- Bacteria
- fat
- crystals
22
Q
When is bacteria in urine sediment significant?
A
- Voided and catheterized samples may have some contaminant bacteria
- Cystocentesis samples should have NONE
- Bacteriuria representing and infection is usually accompanied by pyuria
23
Q
What does Crystalluria indicate?
A
Urine is supersaturated with compounds that comprise the crystals
may be seen in health or disease
24
Q
What are Struvite Crystals?
A
- Magnesium ammonium phosphate or tripple phosphate cyrstals
- Colorless
- 3-D prism-like (coffin lids)
- Often in urine of healthy animals
- Prefer neutral to alkaline urine - can form in any pH
- Bacterial cystitis predisposes to struvite crystaluria and urolithiasis
25
What are Calcium Oxalate Dihydrate Crytals?
* Colorless squares with corners connected by a central ‘X’
* Can develop in **any pH**
* See often in healthy animals
* Can develop in stored urine
* With or without calcium oxalate urolithiasis
* secondary to abnormal calcium excretion
26
What are Bilirubin Crystals?
* May be associated with bilirubinuria & bilirubinemia
* Fine needle-like crystalline structure
* Dogs:
* Fairly common in highly concentrated urine
* Often not clinically significant
* Cats, horses & cattle
* Pathologically significant
* Disorders that cause bilirubinuria
27
What are Calcium Carbonate crystals?
* 2 forms:
* Large yellow-brown or colorless spheroids with radial striations
* Smaller round, ovoid to dumbbell-shaped
* Common in urine of normal horses, rabbits, guinea pigs, & goats
* In dogs and cats with renal disease:
* need to rule or melamine-cyanuric acid crystals
28
What are Urate Cystals?
* Uric Acid & ammonium urate/biurate
* Predisposed with Portosystemic shunts
* with or without urate uroliths
* Other hepatic disease where hyperammonemia exists
* Dalmatians & English bulldogs prone
* decreased degradation of uric acid to allantoin via uricase
29
What are Calcium Oxalate Monohydrate Crystals?
* Indicate supersaturation with calcium and oxalate
* **Hemp-seed, or dumbbell shaped**
* Can be seen in a low # in health
* **Flat, six-sided form** (fence pickets)
* **Ethylene glycol poisoning** - not always seen
* May also be seen with other causes of hypercalciuria
30
What are some of the less common crystals that can be found in urine sediment?
* Cystine Crystals
* Flat, colorless, hexagonal
* often aggregate in layers
* form in acidic urine
* Inherited sex-linked metabolic abnormality resulting in tubular inability to reabsorb cystine and occasionally other AA
* avoid breeding affected animals
* Drug Associated Crystals
* Sulfas, ampicillin, radiopaque contast agents
31
What are Casts?
* Form in the distal tubules and collecting ducts
* Cylindrical molds - composed mainly of Tamm-Horsefull mucoprotein
* Named according to composition
* Cellular, granular & waxy casts represent different stages of cell degeneration
* How casts appear depends upon the length of time it was in the tubules prior to being shed
32
What are Casts?
* Form in the distal tubules and collecting ducts
* Cylindrical molds - composed mainly of Tamm-Horsefull mucoprotein
* Named according to composition
* Cellular, granular & waxy casts represent different stages of cell degeneration
* How casts appear depends upon the length of time it was in the tubules prior to being shed
33
What are Hyaline Casts?
* Form in the absence of cells in the tubular lumen
* Protein only
* Rounded ends and parallel sides are diagnostic features
* often cigar-shaped
* Few (\<2/lpg) may be seen in urine of healthy animals
* High #s associated with proteinuria - not always seen
* especially glomerular proteinuria
34
What are epithelial cell casts?
* Desquamation of epithelium form renal tubules
* Cast is shed shortly after being formed
* Cells appear intact and indicate renal disease
* Result form
* Ischemia
* infarction
* nephrotoxicity (aminoglycosides, amphotericin B)
* Earliest indicator of renal tubular cell injury when drugs potentially damaging to kidney are used
* NOT seen normally
35
What are Granular Casts?
* Degenerated cellular casts (epithelial, WBC, RBC)
* Low numbers in health after exercise associated with protein metabolism
* Large #s may indicate tubular degeneration consistent with:
* nephritis
* nephrotoxin
* infection
* protein losing nephropathy
36
What are Waxy Casts
* Long standing franular casts
* Have sharp squared-off ends
* Smooth consistency, but more refractile than hyaline casts
* Generally indicate **chronic tubular lesions**
* often associated with severe renal disease
* glomerulonephritis
* amyloidosis
* NOT seen normally
* ALWAYS PATHOLOGIC
37
What are Waxy Casts
* Long standing franular casts
* Have sharp squared-off ends
* Smooth consistency, but more refractile than hyaline casts
* Generally indicate **chronic tubular lesions**
* often associated with severe renal disease
* glomerulonephritis
* amyloidosis
* NOT seen normally
* ALWAYS PATHOLOGIC
38
Do casts correlate with the severity of disease?
* NO
* Large #s
* always indicate active generalized renal disease
* usually acute, but may be reversible or irreversible
* Casts are intermittently shed
* lack of casts does NOT rule out renal disease
