Lab evaluation quiz Yourself Flashcards
Question 1: A 5-week-old puppy has a PC of inappropriate elimination. The urine dipstick has a 2+ glucosuria and the patient is normoglycemic. What next?
A. Do nothing
B. Run serum fructosamine
C. Fractional excretion study
D. Urine culture and sensitivity
E. Screen for low molecular weight protein loss
A. Do nothing - Yes! Glucosuria is anticipated in young dogs due to tubular immaturity. Calves are the only ones born with near-adult tubular function.
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B. Run serum fructosamine – no, this is not diabetes mellitus
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C. Fractional excretion study – no, he’s just got immature tubules and fractional excretion studies are very challenging to “get right”
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D. Urine culture and sensitivity – UTI is unlikely, so, no
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E. Screen for low molecular weight protein loss – this would be similar to the fractional excretion study. Its unnecessary as tubular immaturity is anticipated on a puppy up to 8 weeks of age.
Question 2: Which of the following contribute to urine specific gravity? Select all that apply.
A. Urea
B. Bacteria
C. Creatinine
D. Electrolytes
A. Urea – Yes. It’s a crummy osmol but still contributes half of the medullary concentration gradient!
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C. Creatinine – Yes. It’s dissolved in plasma and therefore, also dissolved in the ultrafiltrate.
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D. Electrolytes - – Yes. They are dissolved in plasma and therefore, also dissolved in the ultrafiltrate.
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B. Bacteria – No. These are suspended in urine, not dissolved in it, so they do not contribute to USG (but if there are lots of them, it can make the line harder to read on the refractometer
Question 3: Which of the following interfere directly with the luminal membrane translocation of aquaporin? Select all that apply.
A. Ethanol
B. Hypokalemia
C. Glucorticoids
D. Hypercalcemia
A. Ethanol – No. This acts centrally to inhibit ADH. Decreased ADH means that water leaves the body. This is why they offer salted peanuts at the bar.
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B. Hypokalemia - Yes
C. Glucorticoids - Yes
D. Hypercalcemia – Yes
I don’t know if I’d ask you an exam question exactly like this, but it’s useful to remember that low potassium, endogenous or exogenous glucocorticoids, and hypercalcemia can all result in polyuria and isosthenuria. In the case of endogenous glucocorticoids, as with hyperadrenocorticism, there’s also a component of hypertension.
Question 4: Which of the following pre-renal causes of proteinuria might NOT abate with appropriate therapy.
A. Hyperadrenocorticism
B. Hyperthyroidism
C. Fever
A. Hyperadrenocorticism
“Over 75% of dogs with untreated Cushing’s syndrome have systemic arterial hypertension and half have proteinuria. Unfortunately,
both hypertension and proteinuria may persist despite successful treatment of the hypercortisolemia.” – endocrine blogspot.
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B. Hyperthyroidism – when therapy is adequate, the proteinuria is expected to abate.
C. Fever – this causes transient proteinuria, which abates with resolution of fever.
Question 5: A dog with increased steroid ALP has a urine cortisol:urine creatinine ratio of 20 x10-6/L. What is the correct interpretation of this result?
A. Normal adrenal function
B. Hyperadrenocorticism
C. Hypoadrenocorticism
D. Insufficient data
A. Normal adrenal function – we cannot know with only this piece of information (it could be stress and pain of illness from something outside the adrenals, for example)
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B. Hyperadrenocorticism – while the result indicates a true increase in cortisol in the body and leaving the body, we cannot diagnose hyperadrenocorticism with only this piece of information.
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C. Hypoadrenocorticism – this is ruled out by this result (you can’t have high cortisol within and leaving the body if you’ve got hypoadrenocorticism
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D. Insufficient data – yes, although we are highly suspicious of HAC, this result cannot be interpreted alone, and further tests are required to arrive at a definitive diagnosis.
Question 6: A 6-year-old, FS, DSH is positive for leukocytes on the dipstick, but neither WBC nor bacteria were identified on the microscopic urine examination. What is the correct interpretation of this result?
A. Occult UTI
B. Insufficient data
C. Unlikely to have UTI
C. Unlikely to have UTI
The point of this question is to see whether you remembered one of the 3 things we ignore on the urine dipstick in veterinary species: USG, nitrites, and leukocytes. Human WBC have different components to non-human animal WBC, so the pad doesn’t react appropriately and we have to confirm WBC by looking at the urine.
Question 7: Match the diagnosis with the laboratory findings:
Hemoglobinuria
Myoglobinuria
Hematuria
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A. PCV normal
B. PCV decreased
C. Plasma straw
D. Plasma pink
E. Plasma brown
F. Urine supernatant straw
G. Urine supernatant red
H. Urine supernatant red/brown
I. AST & CK normal
J. AST & CK increased
Hemoglobinuria
- B, D, G, I
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Myoglobinuria
- A, C, H, J
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Hematuria
- A/B, C, F, I
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I’m not a fan of matching questions on exams. What I would do on an exam is to give you a case where there’s a positive blood result on the dipstick and ask you to tell me whether it’s hemoglobinuria (hemolytic anemia), myoglobinuria (extreme muscle damage), or hematuria (some reason for bleeding in the genitourinary tract).
Question 8: On a urine sediment examination (cystocentesis) a FS dog has 8-10 WBC / hpf but no bacteria observed. What is the correct interpretation?
A. Insufficient data
B. Urinary tract infection
C. No UTI, no bacteria observed
B. Urinary tract infection – yes, this question is asking you to recall that it takes 10k rods or 100k cocci per mL of urine before they will reliably spin down in the sediment (you’d need an ultracentrifuge to make them spin down)
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A. Insufficient data – This is enough data to say she’s got a UTI
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C. No UTI, no bacteria observed – Nope, just because we don’t see them doesn’t mean they aren’t there. And sometimes we could have a mural bacterial cystitis, too.
Question 9: On a urine sediment examination (cystocentesis) a FS dog has 2 fine granular casts / lpf. USG was 1.010. What is the correct interpretation?
A. Tubular damage
B. Insufficient data
C. Insignificant, 2 casts / lpf is ok
A. Tubular damage – Yes. 2 fine granular casts / 10x field is only acceptable if the animal is hitting their minimal concentrating ability (1.030 in dogs, 1.035 in cats, 1.025 in horse and ruminants)
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B. Insufficient data – No, this is sufficient data to make a diagnosis
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C. Insignificant, 2 casts / lpf is ok - 2 fine granular casts / 10x field is only acceptable if the animal is hitting their minimal concentrating ability
Question 10: A cat is in good body condition with a normal PCV. She has azotemia, hyperkalemia, and isosthenuria (scant urine present). What is the most likely diagnosis?
A. Insufficient data
B. Acute kidney injury
C. Chronic kidney disease
D. Normal kidney function
B. Acute kidney injury – Yes! Hx = acute. Good body condition, no anemia = acute. Hyperkalemia = acute oliguric / anuric kidney injury. Isosthenuria = kidney injury (could be acute or chronic, but all the other data tells us it’s acute)
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Question 11: Name three non-renal reasons for isosthenuric urine (i.e., when it isosthenuria not the kidney’s fault?)
- Administration of diuretics
- Administration of IV fluids
- Diabetes mellitus (diuretic effect of glucose)
- Hyperthyroidism / hyperadrenocorticism / administration of pred (or other glucocorticoid)
- Pyometra / UTI
- Medullary washout (it does happen, so don’t discount it as a possible answer out
in the real world – a good history can help!) - Hypercalcemia
- Tubular damage from infection or damage caused by drug administration
- Tubular immaturity in young non-human animals (except calves)
- Inherited tubular transport protein defects (e.g., Basenjis)
