Lect. 19 - Exam 3 Renal Part 1

Question 1

How do we classify azotemia?

Answer 1

Pre renal azotemia
Renal azotemia
Post renal azotemia

Question 2

1. Where does Pre-renal azotemia occur?
2. The #1 cause of pre-renal azotemia is _________, followed by ______ and ______________ disease.
   - Hypovolemia leads to decreased renal __________ –> reduced _____.
3. On bloodwork, you will often see increased ____ and ________ together, but not always.
4. Pre-renal azotemia typically resolves with ______/_____ therapy, but can lead to ______ damage if not corrected.

Answer 2

1. Pre-renal azotemia occurs before the kidney
2. The #1 cause of pre-renal azotemia is dehydration, followed by shock and Cardiovascular disease.
   - Hypovolemia leads to decreased renal perfusion –> reduced GFR.
3. On bloodwork, you will often see increased BUN and creatinine together, but not always.
4. Pre-renal azotemia typically resolves with hydration/fluid therapy, but can lead to kidney damage if not corrected.

Question 3

1. The Urine specific gravity in a case of Pre-renal azotemia is often _________.
   - Pathogenesis: Hypovolemia –> increased _____ secretion
2. What are the USG threshold values for the species listed below?
   - Dogs: ______
   - Cats: ______
   -Cattle and horses: _____
   - Birds: ______
3. How would you describe a pre-renal azotemic patient’s urine output?
4. On CBC, what would you notice about their RBC count?
5. On the Chemistry panel, what do you notice about the albumin level?

Answer 3

1. hypersthenuric
2. ADH
   - Dogs: >1.030
   - Cats: >1.035
   - Cattle and horses: >1.025
   - Birds: >1.020
3. Often oliguric, meaning their output is very low
4. erythrocytosis (increased RBC count)
5. hyperalbuminemia

Question 4

1. Where in the body does Renal azotemia occur?
2. Increased _____ and/or _______ due to decreased ____ from reduced ______ function (remember: need ___% functional nephron loss).
3. In Ruminants, we may only see elevated _______ (urea is excreted in the _______)

Answer 4

1. The kidneys are the problem
2. Increased BUN and/or creatinine due to decreased GFR from reduced nephron function (remember: need 75% functional nephron loss).
3. Ruminants: may only see elevated creatinine (urea is excreted in the rumen)

Question 5

1. The USG in a case of Renal azotemia
   is described as?
2. Urine status depends on the ______ disease
   – More common to see _______ with chronic kidney disease;
   - More common to see ______ with acute kidney disease
3. What is a concurrent disease commonly associated with renal azotemia?
4. Patients with kidney disease are often ______
5. What happens to the USG if a patient has pre-renal and renal azotemia?

Answer 5

1. Isosthenuria (1.008-1.012)
2. underlying
   – More common to see polyuria with chronic kidney disease;
   - More common to see oliguria with acute kidney disease
3. pre-renal azotemia
4. dehydrated
5. The USG should still be in the isosthenuric range if both are present

Question 6

1. In a case Renal azotemia, we will see ____________ anemia.
2. Chemistry panel:
   - Phophorous levels = ________
   
   • _____ GFR
     - Amylase/Lipase levels = _________ amylase and/or lipase
   • ______ GFR
     - Albumin levels = ________
   • Albumin loss through _____ or _____
     - Titrational metabolic _______
   • Titration of _____ acids, _____ acids, or _______ ______

Answer 6

1. non-regenerative
2. • Phophorous levels = Hyperphosphatemia
   • Decreased GFR
     - Amylase/Lipase levels = Increased amylase and/or lipase
   • Decreased GFR
     - Albumin levels = Hypoalbuminemia
   • Albumin loss through glomerulus or tubules
     - Titrational metabolic acidosis
   • Titration of uremic acids, lactic acids, or ethylene glycol

Question 7

When the kidneys are damaged, they produce less __________ (____), a hormone that signals your _____ ______. With less _____, your body makes fewer _____, and less ______ is delivered to your organs and tissues.

Answer 7

When the kidneys are damaged, they produce less erythropoietin (EPO), a hormone that signals your bone marrow. With less EPO, your body makes fewer red blood cells, and less oxygen is delivered to your organs and tissues.

Question 8

1. If a Renal azotemia patient is polyuric, how does this affect their potassium?
2. If a Renal azotemia patient is anuric, how does this affect their potassium?
3. If a Renal azotemia equine patient is oliguric, how does this affect their calcium? Explain the pathogenesis.
4. If a Renal azotemia patient is oliguric, how does this affect their calcium? Explain the pathogenesis.
5. How are sodium and chloride levels affected in cattle and horses suffering from renal azotemia?

Answer 8

1. Hypokalemia
2. Hyperkalemia
3. Hypercalcemia
   - Calcium carbonate crystals in equine urine. Horses excrete Ca into urine –> lack of excretion due to decreased GFR
4. Hypocalcemia (most other species)
   Increased excretion and decreased calcitriol production
5. Hyponatremia and hypochloridemia

Question 9

What can be seen in the image below?

Answer 9

Calcium carbonate (unstained) in equine urine sediment

Question 10

How are the following parameters affected in a case of Renal azotemia?
1. Protein. Also describe where this is occurring in the body.
2. How is protein measured? What does this test measure?
3. What is the Urine protein to creatinine (UPC) ratio?
4. How is albumin affected?

Answer 10

1. Proteinuria – either glomerular or tubular protein loss.
2. Protein measured on dipstick (trace to 4+ scale); low sensitivity and low specificity. Primarily detects Albumin
3. The normal is <0.5
4. Microalbuminuria – more sensitive detection of albumin in the urine
   <30 mg/dL

Question 11

Renal azotemia: ACUTE vs CHRONIC disease

Question 12

What are the causes of renal azotemia?

Answer 12

1. Inflammatory conditions
   - Glomerulonephritis, pyelonephritis
2. Renal amyloidosis
3. Toxic nephrosis
   - Hypercalcemia, ethylene glycol, myoglobin, gentamicin, phenylbutazone
4. Renal ischemia or hypoxia
5. Congenital hypoplasia or aplasia
6. Hydronephrosis
7. Neoplasia (primary renal, or metastatic)

Question 13

What are the differences in the parameters listed below for Glomerular vs Tubular renal disease?
1. Proteinuria
- Urine dipstick value?
- UPC value?
- Clinically may see?
2. Diseases to consider?

Answer 13

See below

Question 14

1. Where in the body does Post-renal azotemia occur?
2. Post-renal azotemia is often due to?
   - Outflow _______ or ____ in outflow tract:
   A. _____, ______ or ______ obstructions
   - _______, urethral ____ in cats, _____, ______ disease
   B. Ruptured _______ – uroabdomen
   - Can confirm the diagnosis by measuring creatinine concentration on the _______/_______ fluid –> typically greater than _________ creatinine
3. Urine specific gravity is highly _______
   - Diagnosis made more from _____, ____, and _____ findings than from laboratory tests
4. Often ____ or _____

Answer 14

1. It is after the kidney and not the kidney
2. lower urinary tract disease.
   - Outflow obstruction or rupture in outflow tract:
   A. Ureteral, bladder or urethral obstructions
   - Urolithiasis, urethral plugs in cats, neoplasia, prostatic disease
   B. Ruptured bladder – uroabdomen
   - Can confirm the diagnosis by measuring creatinine concentration on the abdominal/peritoneal fluid –> typically greater than serum creatinine
3. Urine specific gravity is highly variable
   - Diagnosis made more from history, PE, and imaging findings than from laboratory tests
4. Often anuric or oliguric

Question 15

Question 16

When classifying azotemia, you want to look at the:
1. _____:_______ ratio to classify azotemia as pre-renal, renal, post-renal
- Should be regarded as a crude index of renal function because it lacks diagnostic _______ and _______ for renal dysfunction caused by renal disease

Answer 16

BUN:creatinine ratio to classify azotemia as pre-renal, renal, post-renal
- Should be regarded as a crude index of renal function because it lacks diagnostic sensitivity and specificity for renal dysfunction caused by renal disease

Question 17

_______ BUN and ______ creatinine suggests pre-renal azotemia

Answer 17

Increased BUN and normal creatinine suggests pre-renal azotemia

Question 18

If creatinine is increased ________ more than BUN, the azotemia is probably renal or post-renal

Answer 18

If creatinine is increased proportionately more than BUN, the azotemia is probably renal or post-renal

Question 19

The USG measures the kidney’s Ability to _______ and ______ Urine. It requires ~____% functional nephrons.
Dependent upon:
1. Production and responsiveness to ____ (_________)
2. Maintaining medullary ____________
Production of _____ (_____)
Production of _________ (____)

Answer 19

The USG measures the kidney’s Ability to Concentrate and Dilute Urine. It requires ~33% functional nephrons
Dependent upon:
1. Production and responsiveness to ADH (Vasopressin)
2. Maintaining medullary hypertonicity
Production of urea (BUN)
Production of aldosterone (Na+)

Question 20

USG measures the _______ of urine with respect to ______. It is an estimate of the urinary ______ and _____ capacity.
- Approximates urine _______
- Measured with a _______
- Interpreted alongside _____, _____, and the patient’s ________ status
- Collect blood and urine at the same time.

Answer 20

USG measures the density of urine with respect to water. It is an estimate of the urinary concentrating and diluting capacity.
- Approximates urine osmolality
Measured with a refractometer
Interpreted alongside BUN, CREA, and the patient’s hydration status
- Collect blood and urine at the same time.

Question 21

Obtain a urine sample & measure USG when:
1. ________ renal disease
2. _____ wellness
3. Hx of ___/___
4. Animal is not _________
5. Animal is not __________

Answer 21

Obtain a urine sample & measure USG when:
1. Suspected renal disease
2. Geriatric wellness
3. Hx of PU/PD
4. Animal is not dehydrated
5. Animal is not azotemic

Question 22

Most refractometers measure from ?
- 0.000 = ?
- The higher the urine specific gravity, the more __________ the urine
“Normal” or “threshold” values vary by species: if the USG is above this value, Urine is ADEQUATELY concentrated
Dogs: >1.030
Cats: >1.035
Cattle and horses: >1.025
Birds: >1.020

Answer 22

Most refractometers measure from 0.000-1.040
- 0.000 = deionized water
- The higher the urine specific gravity, the more concentrated the urine
“Normal” or “threshold” values vary by species: if the USG is above this value, Urine is ADEQUATELY concentrated
Dogs: >1.030
Cats: >1.035
Cattle and horses: >1.025
Birds: >1.020

Question 23

1. Hyposthenuria USG ≤____ (____ urine)
   - Kidney is actively _____ urine, does NOT indicate renal __________
2. Isosthenuria USG _______-________
   Kidney is not adjusting urine ______ (non concentrating nor diluting)
3. Hypersthenuria (______ urine)
   ≥_____ Dog
   ≥______ Cat
   ≥_______ Equine, Ruminants, Porcine

Answer 23

1. Hyposthenuria USG ≤1.007 (dilute urine)
   - Kidney is actively diluting urine, does NOT indicate renal insufficiency
2. Isosthenuria USG 1.008-1.012
   Kidney is not adjusting urine concentration (non concentrating nor diluting)
3. Hypersthenuria (concentrated urine)
   ≥1.031 Dog
   ≥1.035 Cat
   ≥1.025 Equine, Ruminants, Porcine

Question 24

USG
“Gray zone” = inadequately concentrated* In between isosthenuria and hypersthenuria, e.g. _____-_____ in the dog* This value may or may not be appropriate –depends on the individual patient

Answer 24

USG
“Gray zone” = inadequately concentrated* In between isosthenuria and hypersthenuria, e.g. 1.013-1.029 in the dog* This value may or may not be appropriate –depends on the individual patient

Question 25

Range of minimal concentration (ROMC)
______-______ Dog
______-_______ Cat
_______-_______ Equine, Ruminants, Porcine

Answer 25

Range of minimal concentration (ROMC)
1.013-1.030 Dog
1.013-1.034 Cat
1.013-1.024 Equine, Ruminants, Porcine

Question 26

When you have a number that does not make sense…(i.e. USG does not reflect the patient’s hydration status, the BUN, and/or the CREA)
First, get another sample. Is it reproducible?
No.
Original measurement is not significant.
Yes. Ask yourself:
Are there particles interfering with the refractometer? (glucose, ketones, mannitol, etc.)

Question 27

USG Interpretation

Animals with RENAL disease has Impaired urine _______ before _______:
~66% functional nephron loss –> impaired urine ________ (USG)
~75% functional nephron loss –> impaired urine _______ + _______

Answer 27

Animals with RENAL disease has Impaired urine concentration before azotemia:
~66% functional nephron loss –> impaired urine concentration (USG)
~75% functional nephron loss –> impaired urine concentration + azotemia

Question 28

List the causes of impaired urine concentrating ability other than kidney disease.

Answer 28

1. Central diabetes insipidus
2. Nephrogenic diabetes insipidus
3. Diseases that cause polyuria and medullary washout

Question 29

Central diabetes insipidus
Pituitary disease causes lack of ______ secretion –> collecting duct does NOT ________ water

Answer 29

Central diabetes insipidus
Pituitary disease causes lack of ADH secretion collecting duct does NOT reabsorb water

Question 30

Nephrogenic Diabetes Insipidus
- ADH is being secreted by the pituitary, but the kidneys are ________ to it.
A. Primary tubular defects
B. Secondary effect of other diseases:

Answer 30

Nephrogenic Diabetes Insipidus
ADH is being secreted by the pituitary, but the kidneys are unresponsive to it
Primary tubular defects
Secondary effect of other diseases:
Hypercalcemia
Hypokalemia
Cushing’s disease (hyperadrenocorticism)
Endotoxemia (such as E. coli pyometra)

Question 31

3. Diseases that cause polyuria and medullary washout

Answer 31

LOL How Fucked Does This Pain Feel?

Question 32

Test of renal urine concentrating ability

1.Abrupt water deprivation test
- Animal is abruptly deprived of water, and USG is monitored and stopped if concentration becomes adequate (__________)
-Determines if polyuria is due to ___________
2.Gradual water deprivation test
- Similar to AWDT, but occurs over several days for the kidneys to re-establish ?
- For ___/____ cases with suspected medullary washout
3.ADH response test
- Differentiates between _______ and _______ diabetes insipidus
4.Modified water deprivation test–hybrid of WDT and ADH response test
- Differentiates 3?

Answer 32

Test of renal urine concentrating ability

1.Abrupt water deprivation test
- Animal is abruptly deprived of water, and USG is monitored and stopped if concentration becomes adequate (hypersthenuric)
-Determines if polyuria is due to polydipsia
2.Gradual water deprivation test
- Similar to AWDT, but occurs over several days for the kidneys to re-establish medullary hypertonicity
- For PU/PD cases with suspected medullary washout
3.ADH response test
- Differentiates between nephrogenic and central diabetes insipidus
4.Modified water deprivation test–hybrid of WDT and ADH response test
- Differentiates psychogenic polydipsia, central DI, and nephrogenic DI

Question 33

Answer 33

D

Question 34

Answer 34

B, C, D

Question 35

Name 3 non-renal reasons for isosthenuric urine

Answer 35

Administration of diuretics, administration of IV fluids, diabetes mellitus, medullary washout. There are others we have not talked about: hypercalcemia, tubular damage from infection or damage caused by drugs, tubular immaturity in young animals (except calves), hyperadrenocorticism, hyperthyroidism, administration of glucocorticoid)