Renal Biochemistry Flashcards
tests for renal function
urinalysis
UPC
GFR
BUN
creatinine
BUN/creatinine ratio
SDMA
electrolytes
UPC definition
urine protein creatinine ratio
GFR definition
glomerular filtration rate
BUN definition
blood urea nitrogen
what is GFR
flow rate of filtered fluid through the kidney
why is it hard to directly measure GFR in animals
no standardized body surface area in animals
what is urea
the principal end product of amino acid breakdown in mammals
what is BUN
normally, all blood urea passes into the filtrate and approx 1/2 is reabsorbed
why can measuring BUN give us insight into renal function
it can show us how well the kidneys are filtering blood
in which types of animals is BUN less helpful
ruminants due to use of urea in digestive process
causes for decreased BUN
starvation, over hydration, glucosuria
causes for increased BUN
increased formation
decreased delivery to kidneys
impaired elimination
artifact
what can a normal BUN indicate
healthy animal, subclinical renal disease, renal failure in ruminants and horses
can a BUN within normal limits occur in an animal with kidney disease
yes, ruminant GI microbial utilization of BUN
what is creatinine
formed from creatine
in skeletal muscle, diffuses into blood
is creatinine a sensitive indicator of kidney function
no, nearly 75% os kidney tissue would need to be nonfunctional before levels rise
can we use creatinine to evaluate renal function in birds
no
causes for increased creatinine
severe muscle exertion/damage or dehydration
causes for decreased creatinine
decreased muscle mass
what can changes in BUN/creatinine ratio indicate
diet, GI hemorrhage, pre-renal azotemia
is SDMA a sensitive marker for GFR
yes
why is SDMA more sensitive than creatinine
increases sooner when there is kidney damage
what are some common electrolyte alterations with renal disease
hyperphosphatemia
hyperkalemia/hypokalemia
hypochloremia
hypocalcemia/hypercalcemia
hyperphosphatemia
increase in phosphorus
hyperkalemia
increased potassium
hypokalemia
decreased potassium
hypocloremia
decrease in chloride
hypocalcemia
decrease in calcium
hypercalcemia
increase in calcium
which electrolyte/mineral alterations are commonly seen with acute renal failure
hyperkalemia and hyperphosphatemia
which electrolyte/mineral alterations are commonly seen with chronic renal failure
hypokalemia, hypocalcemia, hypercalcemia
renal insufficiency definition
reduction in renal function without clinically detectable retention of BUN/creatinine in blood
what percentage of nephrons are lost in renal insufficiency
66%
renal failure definition
reduction in renal function with BUN/creatinine in blood
what percentage of nephrons are lost in renal failure
over 75%
3 categories of azotemia
pre-renal
renal
post-renal
pre-renal azotemia causes
decreased cardiac output, dehydration, increased protein catabolism, high protein diets, GI bleeds
renal azotemia causes
renal failure
post-renal azotemia causes
urinary tract obstruction
urinary tract rupture
what other test values can help determine which type of azotemia is occurring
GFR and urine specific gravity
what is uremia
clinical manifestations associated with renal failure
are all animals who are azotemic also uremic
no
are all animals who are uremic also azotemic
yes
onset of ARF vs CRF
ARF - rapid (days/hours)
CRF - slow (months/years)
etiologies of ARF vs CRF
ARF - infection, neoplasia, toxins
CRF - familial, idiopathic
prognosis of ARF vs CRF
ARF - immediately life-threatening, potentially reversible
CRF - progressive, irreversible
kidney size ARF vs CRF
ARF - enlarged and painful
CRF - shrunken and irregular
urine volume ARF vs CRF
ARF - oliguric, anuric, and polyuric
CRF - polyuric
urine sediment ARF vs CRF
ARF - active (inflammatory, RBC, bacteria, casts)
CRF - inactive (maybe casts)
BUN/creatinine ARF vs CRF
ARF - increased
CRF - increased
potassium ARF vs CRF
ARF - normo to hyperkalemic
CRF - normo to hypokalemic
PCV ARF vs CRF
ARF - normal to increased
CRF - decreased
