Flashcards in Urinary Deck (44):
Define concentrating ability:
renal capacity to resorb water in excess of solutes in the glomerualr filtrate
concentrate glomerular filtrate
Define diluting ability:
capacity to resorb solutes in excess of water in teh gloimerular filtate
dilute glomerular filtrate
USG= 1.007 to 1.013
urine osmolality = serum osmolality
concentrated urine >1.013, variable species to species on appropriateness
What produces ADH?
pituitary in response to hypovolemia, hyperosmolality
Where does ADH act?
needs medullary hypertonicity
urea, Na, Cl
Where is aldosterone produced?
Zona Glomerulosa of adrenal gland in response to:
angiotensin 2, ACTH, K+
Acts on Distal/Convoluted Tubules
What does aldosterone do?
Leads to resorption of Na/Cl
K+ is excreted
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
increased non protein nitrogenous compounds in the blood
increased serum creatinine
increased serum urea nitrogen
clinical manifestation of renal failure
Vomiting, wt loss, anemia, oral ulcers, PU/PD
GLomerular filtration rate
rate substance is cleared from plasma
What is GFR depenedent on?
# of functional glomeruli
What are the 4 stages of Renal Disease?
Diminished renal reserve
Chronic Renal insufficiency
Chronic Renal Failure
End Stage Renal Disease
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
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
Define Acute Renal Failure
can be both reversible/non-reversible
abrupt insult that markedly reduced GFR
Toxins, ischemia, infection
T/F magnitude of azotemia is used to differentiate between CRF/ARF
moderate-marked azotemia develops quickly in ARF, takes weeks to months in CRF
What common urine volume is observed in ARF?
oliguria or anuria is common
What makes a solute ideal for measuring GFR?
inulin, iohexol, mannitol
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
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
What non renal factors can affect UN serum levels?
RMT/Horses- additional routes of secretion, diet
Carnivores- mild post-prandial increase, high protein diet
Always interpret urine with ______
URINE SPECIFIC GRAVITY
What causes PRE-RENAL azotemia?
Hypovolemia- dehydration, shock, blood loss
decreased cardiac output- cardiac insufficiency, hypoadrenocorticism
What causes RENAL azotemia?
Primary- inflammation, amyloidosis, toxic, congenital, hypoxia, hydronephrosis, neoplasia
What causes POST-RENAL azotemia?
blockage of excretion, UT obstruction/urine leakage
What is the most important thing used to classify type of azotemia?
Urine Specific Gravity
extrarenal factors interferring w/ concentrating ability
If a given species of animal has azotemia, what would you expect thier USG be if they have an appropriate response
IF USG is > than the expected value, what can you conclude?
The animal is responding, kidneys are doing their job
IF USG is
Something is wrong, impaired concentrating ability
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
What is FE?
sodim most commonly measured
______ damage increases FE
______ decreases FE
Tubular damage increases FE
Pre-renal azotemia decreases FE
Hyperphosphatemia occurs with decreased GFR in ______
Dogs and Cats
T/F phosphorus is the single most important electrolyte in RMT classification of azotemia
Super false... it doesnt tell you shit
Hypophosphatemia is indicative of renal failure in which species?
Decreased in GFR results in Hypercalcemia in _____
Hypocalcemia resulting from renal failure occurs in:
Dogs, Cats, RMT
EXCEPT sometimes small animals have the opposite occur in congenital renal dz
What is the threshold/formula for determining soft tissue mineralization?
>70 Watch out
What does Magnesium tell you?
Nothing you have to read the test results
hypermag occurs with decreased GFR
Hyperkalemia occurs with impaired renal function in:
dogs, cats, horses