Renal Flashcards
(211 cards)
4 things GFR depends on:
1) adequate blood flow, 2) BP, 3) interstitial and intratubular pressures, 4) number of functioning nephrons
GFR has to be decreased by ____% before BUN and Cr increase.
75%
Urine concentrating ability is lost after ___% of nephrons are gone.
66%
After creatinine is increased, every doubling of Cr means there’s been loss of function of ___% of the remaining renal mass.
50%
What are some tests used to measure GFR?
endogenous/exogenous Cr clearance
insulin clearance
clearance of radioisotopes
measurement of fractional clearance of electrolytes
What is the formula for Cr clearance?
Cr clearance= [(Urine Cr x vol urine/time/kg)/ serum Cr]
What are 4 reasons that Cr is better than BUN for determining GFR.
1) rate of production and exertion of Cr is constant, 2) Cr isn’t metabolized by external or renal processes, 3) some BUN in the filtrate is reabsorbed, 4) rate of BUN resorption varies w/hydration status and speed of flow in tubules
Between BUN and Cr, which can be disproportionately higher in dehydration? Why?
BUN (rate of BUN resorption varies w/hydration status and speed of flow in tubules)
What does an increased BUN:Cr ratio indicate? (2)
dehydration of intestinal bleeding
What does a decreased BUN:Cr ratio indicate? (3)
diuresis, noncreatinine chromagens, or ability of cows/horses to excrete BUN from GI
What are the 5 locations that can have lesions leading to renal azotemia?
glomeruli, tubules, interstitium, renal pelvis, blood vessels
Creatinine: Made in the ____ from the spontaneous conversion of ____ and ____.
Made in the muscles from the spontaneous conversion of creatine and creatine phosphate.
What is a major mechanism of non-renal increases in Cr?
muscle catabolism
What are 3 scenarios where you could have incr Cr from incr muscle catabolism.
Sepsis, developing cachexia, rhabdomyolysis
What is are 3 scenarios where you could have dear Cr?
liver failure (rare), cachexia, hyperthyroidism
What should you think about in cattle and horses if the Cr is significantly increased and the BUN is normal or a little high?
Non-creatinine chromagens
What are 4 important non-creatinine chromogens?
ketones, glucose, carotenes, Vit A
Interpret the scenario in a cow/horse:
USG & Cr incr, BUN normal
non-Cr chromagens causing Cr increase
Interpret the scenario in a cow/horse:
USG & BUN incr but Cr disproportionately higher than BUN
prerenal azotemia & non-Cr chromagens causing incr
Interpret the scenario in a cow/horse:
Isosthenuria w/azotemia but Cr disproportionately higher than BUN
renal azotemia but the discrepancy could be b/c of non-Cr chromogens or the fact that they can excrete BUN in GI
Between BUN and Cr, which will be present in the abdominal fluid of an animal with ruptured bladder longer and why?
Cr b/c it takes longer for Cr to equilibrate with serum than BUN
Dialysis and diuresis promote greater excretion of ___ than ____ (BUN or Cr)
Dialysis and diuresis promote greater excretion of BUN than Cr.
___% of BUN is passively resorbed by the proximal tubules, ___% by the collecting ducts.
50% of BUN is passively resorbed by the proximal tubules, 10% by the collecting ducts.
What happens to the urea secreted in saliva of small animals?
goes to GI–> degraded to ammonia by back–> reabsorbed–> to liver–> turned back into urea