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Flashcards in Urinary Deck (44):
1

Define concentrating ability:

renal capacity to resorb water in excess of solutes in the glomerualr filtrate

concentrate glomerular filtrate

2

Define diluting ability:

capacity to resorb solutes in excess of water in teh gloimerular filtate

dilute glomerular filtrate

3

Define Isosthenuria:

USG= 1.007 to 1.013

urine osmolality = serum osmolality

4

Define Hyposthenuria:

USG

5

Define Hypersthenuria:

concentrated urine >1.013, variable species to species on appropriateness

6

What produces ADH?

pituitary in response to hypovolemia, hyperosmolality

7

Where does ADH act?

collecting tubules

aquaporins/water resorption

needs medullary hypertonicity
urea, Na, Cl

8

Where is aldosterone produced?

Zona Glomerulosa of adrenal gland in response to:

angiotensin 2, ACTH, K+

Acts on Distal/Convoluted Tubules

9

What does aldosterone do?

Leads to resorption of Na/Cl

water follows

K+ is excreted

10

What 3 things are required by the kidney to concentrate urine?

ADH- hyperosmolality, hypovolemia, increased angiotensin

Epithelial cells in CT that are responsive to ADH

Medullary hypertonicity- osmolality of the medullary interstitial fluid must exceed that of the tubular fluid

11

Define azotemia

increased non protein nitrogenous compounds in the blood

increased serum creatinine

increased serum urea nitrogen

12

Define uremia

clinical manifestation of renal failure

Vomiting, wt loss, anemia, oral ulcers, PU/PD

13

Define GFR:

GLomerular filtration rate

rate substance is cleared from plasma

14

What is GFR depenedent on?

blood volume

cardiac output

# of functional glomeruli

vessel constriction/dilation

15

What are the 4 stages of Renal Disease?

Diminished renal reserve

Chronic Renal insufficiency

Chronic Renal Failure

End Stage Renal Disease

16

Define Chronic Renal Failure:

Loss of concentrating ability may precede azotemia

> 2/3rds loss of functional renal mass you loose concentrating ability

> 3/4 ths loss of functional mass you develop azotemia

17

Why do animals loose concentrating ability in CRF?

more solute presented to remaining functional nephrons

high solute results in solute diuresis

Medullary hypertonicity not maintained

tissue damage, Na/Cl transport to interstitial fluid is decreased, epithelium in distal nephron tubule less responsive to ADH

18

Define Acute Renal Failure

can be both reversible/non-reversible

abrupt insult that markedly reduced GFR

Toxins, ischemia, infection

19

T/F magnitude of azotemia is used to differentiate between CRF/ARF

FALSE

moderate-marked azotemia develops quickly in ARF, takes weeks to months in CRF

20

What common urine volume is observed in ARF?

oliguria or anuria is common

21

What makes a solute ideal for measuring GFR?

freely filtered

not secreted

not resorbed

inulin, iohexol, mannitol

CREATININE

22

What is Creatinine?

small nitrogen based molecule; produced by degredation of creatine, creatine-phosphate

Freely filterd, minimal secretion, species specific

most frequently used to assess renal function, most efficient indirect marker of GFR

BUT it is insensitve

23

What is Urea Nitrogen?

BUN, SUN, UN

pdx by liver from ammonia, hepatic urea cycle

main form of nitrogenous waste in mammals

Eliminated by kidney- freely filtered, some tubule resorption, depends on flow etc

24

What non renal factors can affect UN serum levels?

RMT/Horses- additional routes of secretion, diet

Carnivores- mild post-prandial increase, high protein diet

GI hemmorrhage

25

Always interpret urine with ______

URINE SPECIFIC GRAVITY

26

What causes PRE-RENAL azotemia?

Hypovolemia- dehydration, shock, blood loss

decreased cardiac output- cardiac insufficiency, hypoadrenocorticism

Shock- anaphylactic/septic

GI hemorrhage

27

What causes RENAL azotemia?

Primary- inflammation, amyloidosis, toxic, congenital, hypoxia, hydronephrosis, neoplasia

28

What causes POST-RENAL azotemia?

blockage of excretion, UT obstruction/urine leakage

stones

29

What is the most important thing used to classify type of azotemia?

Urine Specific Gravity

other considerations:
multifactorial azotemia
extrarenal factors interferring w/ concentrating ability

30

If a given species of animal has azotemia, what would you expect thier USG be if they have an appropriate response

Dog
Cat
Horse
RMT

Dog >1.030

Cat >1.040

Horse >1.025

RMT >1.025

31

IF USG is > than the expected value, what can you conclude?

The animal is responding, kidneys are doing their job

32

IF USG is

Something is wrong, impaired concentrating ability

33

What are some external renal causes of impaired concentrating ability in face of azotemia?

Tubules unresponsive to ADH- hyperCa, hypoK, endotoxemia, corticodteroids

solute overload- osmotic diuresis

decreased medullary hypertonicity- hypoNa/Cl, loop diuretics, decreased urea pdx- liver failure

34

What is FE?

fractional excretion

sodim most commonly measured

35

______ damage increases FE

______ decreases FE

Tubular damage increases FE

Pre-renal azotemia decreases FE

36

Hyperphosphatemia occurs with decreased GFR in ______

Dogs and Cats

37

T/F phosphorus is the single most important electrolyte in RMT classification of azotemia

Super false... it doesnt tell you shit

38

Hypophosphatemia is indicative of renal failure in which species?

Horses

39

Decreased in GFR results in Hypercalcemia in _____

horses

40

Hypocalcemia resulting from renal failure occurs in:

Dogs, Cats, RMT

EXCEPT sometimes small animals have the opposite occur in congenital renal dz

41

What is the threshold/formula for determining soft tissue mineralization?

multiply phosphorus/calcium

>70 Watch out

42

What does Magnesium tell you?

Nothing you have to read the test results

hypermag occurs with decreased GFR

43

Hyperkalemia occurs with impaired renal function in:

dogs, cats, horses

44

What happens to K in RMTs?

hypokalemia in azotemia

metabolic acidosis