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Urinary Exam 1 > Clinical Evaluation of GFR > Flashcards

Clinical Evaluation of GFR Flashcards

1
Q

What does Azotemia mean to the practitioner?

A

High BUN and High Creatinine

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2
Q

What are the 3 types of Azotemia?

A

Pre-renal
Renal
Post-renal

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3
Q

Decreased renal perfusion (dehydration, shock, Congestive Heart Failure)

A

Pre-Renal

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4
Q

Secondary to intrinsic renal parenchymal disease

A

Renal

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5
Q

a kidney disorder where numerous cysts enlarge in both kidneys reducing the amount of normal kidney tissue and thereby the kidney’s ability to function normally, leading to kidney failure

A

Renal Parenchymal Disease (PKD)

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6
Q

Impaired elimination from the body (obstruction, ruptured bladder)

A

Post-Renal

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7
Q

Clinical and biological abnormalities that accompany a critical loss of functioning nephrons

A

Uremia

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8
Q

How do we measure kidney function?

A

Clearance

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9
Q

The volume of plasma that would have to be filtered by the glomeruli in 1 min. to produce a certain amount in the urine each min.

A

Clearance

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10
Q

Formula for Clearance

A

C = U V/P

Ux = Urine concentration of x (mg/dl)
Px = Plasma concentration of x (mg/dl)
V = Urine output (ml/min)

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11
Q

What if x is resorbed by the tubules?

A

Cx < GFR, because ↓Ux and ↑Px

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12
Q

What if x is secreted by the tubules?

A

Cx > GFR, because ↑Ux and ↓Px

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13
Q

How are GFR and Clearance Related?

A

Creatinine clearance measurements will consistently be 10 to 20 percent higher than GFR in patients with a normal GFR and progressively higher as the GFR falls

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14
Q

When do we actually need to calculate GFR?

A
  • Patient who is PU/PD WITHOUT azotemia
  • Patient who may have another disease which causes PU/PD
    (hyperadrenocorticism, hyperthyroidism, diabetes mellitus, etc.)
  • Patient that may need a nephrectomy (need to know if other kidney
    is functioning)
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15
Q

What substance (x) do we use?

A
  • Freely filtered at glomerulus
  • Not plasma protein bound
  • Not metabolized
  • Non-toxic
  • Excreted only by kidneys
  • Neither reabsorbed nor secreted by the renal tubules
  • Stable in blood and urine and easily measured

Under these circumstances
CLEARANCE = GFR

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16
Q

Which substance meets all criteria for a good substance to measure Clearance so it = GFR, but difficult to use because must be infused IV over a period of time with constant urine collection?

A

Inulin

(Gold-standard for GFR determination)

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17
Q

Uses patients’ naturally made creatinine
- 24h urine collection (challenge in vet med)
- Slight underestimate of GFR

A

Endogenous - Creatinine Clearance Method

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18
Q
  • Creatinine given SQ or IV in a high dose and 24h urine collection
  • Very good estimate of GFR
A

Exogenous - Creatinine Clearance Method

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19
Q
  • Iodinated water-soluble contrast agent
  • Non-toxic, EXTRAcellular only, little protein binding and removed only by the kidneys
  • Newer and simpler way to estimate GFR in clinical setting
  • Give a specific dose IV
A

Iohexol Clearance

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20
Q

What is a problem with Inulin, Creatinine Clearance Method, and Iohexol Clearance?

A

They measure GLOBAl GFR, Not individual kidney GFR

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21
Q
  • Imaging method to determine individual kidney GFR, effective
    renal plasma flow, and filtration fraction
  • Give the isotope 99mTc-DTPA and image kidneys with a Gammacamera
A

Radioisotopes

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22
Q

What do we use in ‘real life’ (regular practice) to estimate the GFR?

A

BUN and Creatinine

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23
Q

Product of protein and aa catabolism

A

BUN

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24
Q

Made in the LIVER with ammonia from aa’s

A

Blood Urea Nitrogen (BUN)

25
Can be made from endogenous or exogenous proteins
Blood Urea Nitrogen (BUN)
26
Freely permeable across cell membranes, distributed in Total body water
BUN
27
- Renal excretion most important - Filtered at glomerulus - Passively reabsorbed in tubules (most of it) * Less absorbed with rapid flow * More absorbed with slower flow rates
BUN
28
BUN is NOT secreted by ______________
renal tubules
29
- Varies with protein intake and catabolism - Blood level of urea nitrogen reflect renal excretion of urea and protein catabolism - Requires no metabolic work by kidneys - Some degraded by bacteria
BUN
30
- High protein meal - GI bleeding - Increased catabolism - Drugs Are all examples of what?
Non-Renal Factors that INCREASE BUN
31
- Pre-renal – slow tubular flow rates = more reabsorption - Renal - Post-renal
Renal Factors that INCREASE BUN
32
- May reflect high tubular flow rates (lots of urine made) with decreased urea resorption - Low protein diet - Liver dysfunction or portosystemic shunt *Urea not made - Anabolic steroids - slow protein catabolism Are examples of what?
Decreased BUN
33
- Product of muscle breakdown (phosphocreatine) - Produced at a relatively constant rate for an individual
Creatinine
34
Creatinine - Rate of production determined by age, sex, and muscle mass - Young animals have a ___________ creatinine
lower
35
Creatinine - Rate of production determined by age, sex, and muscle mass - Males have a slightly ___________ creatinine
higher
36
Creatinine - Rate of production determined by age, sex, and muscle mass - Well-muscled animals have a __________ creatinine than poorly muscled ones (e.g. Greyhounds)
higher
37
Creatinine - Rate of production determined by age, sex, and muscle mass - ________ (is/is not) influenced by diet
is not
38
Creatinine - Rate of production determined by age, sex, and muscle mass - _________ (is/is not) metabolized in the body
is not
39
Non-Renal: uncommon * Massive muscle necrosis * Prolonged strenuous exercise * Greyhound Norma
Increased Creatinine
40
Renal: Important * Pre-renal – decreased renal perfusion to kidneys (dehydration, shock) * Primary renal – can’t filter (not enough functional nephrons to do the job) * Post-renal – can’t eliminate (obstruction of ureters, urethra, or ruptured urinary tract)
Increased Creatinine
41
- Muscle loss – only one that is really significant (think ancient skinny cats) - Small size - Young age
Decreased Creatinine
42
After eliminating pre-renal and post-renal causes… Increased BUN and Creatinine indicate that at least 75% of ____________ are NOT functioning
nephrons
43
Pre-renal azotemia is usually ________
Mild
44
Post-renal azotemia can be __________
severe
45
What is it that you CAN’T tell from BUN and Creatinine?
- Cause of azotemia - Reversibility of azotemia - Origin of azotemia (pre-renal, renal, post-renal) - Acute vs. chronic disease - Progressive vs. non-progressive disease
46
- Made by all cells and excreted almost exclusively by the KIDNEYS - Increases in the serum earlier than creatinine *EARLIER detection of kidney disease - Not affected by muscle mass
SDMA (IDEXX) Symmetric dimethylarginine
47
When do you get a Urine Specific Gravity?
BEFORE fluids or diuretics are given
48
Localization of Azotemia: *If the animal can concentrate its urine, its NOT ____________ in origin
renal
49
Localization of Azotemia: *If it concentrates but not as much as it should, it is partially ____________ in origin
renal
50
Localization of Azotemia: *If the animal ________ (can/cannot) concentrate its urine, some or all of it is renal in origin (unless drug interference)
cannot
51
The BUN is increased for which types of Azotemia?
- Prerenal - Renal - Postrenal
52
The Creatinine is increased for which types of Azotemia?
- Prerenal - Renal - Postrenal
53
What type of Azotemia is the following? - Increased BUN & Creatinine - USG > 1.030 (concentrated) - BUN, Creatinine is better after IV fluids - Dehydrated - able to urinate - no abdominal fluid - no large firm bladder
Pre-Renal
54
What type of Azotemia is the following? - Increased BUN & Creatinine - USG < 1.030 (not very concentrated) - BUN & Creatinine DOES NOT get better after fluids - Hydrated/Dehydrated (variable) - Able to urinate unless anuric - no abdominal fluid - no large firm bladder
Renal
55
What type of Azotemia is the following? - Increased BUN & Creatinine - USG is Variable - BUN & Creatinine DOES NOT get better after fluids - Hydrated/Dehydrated (variable) - NOT able to urinate - Maybe abdominal fluid - Maybe large firm bladder
Post-Renal
56
normal level of creatinine in cats is:
0.6 and 2.4 mg/dL
57
What are some causes for PU/PD?
- Kidney Disease - Hypercalcemia - Hyperadrenocorticism
58
What MUST be done before moving to a water deprivation test in evaluating PU/PD?
A first morning urine sample specific gravity

Urinary Exam 1 (11 decks)

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