clin path 2 Lab evaluation of renal function Flashcards
what the the important substances that the kidneys want to preserve?
Na, Cl, bicarb, Ca, Mg, Glucose, amino acids, water
acid base balance
water balance
Where does BUN come from?
the liver deaminates amino acids to make urea which moves into the blood.
why BUN a bad indicator of GFR
it can vary with production, readsorption
BUN and ruminants are special
Don’t even bother using it to measure GFR, as the rumen microflora use it to make amino acids
where does creatinine come from
endogenous muscle catabolism (from the break down of creatinine phosphate in energy creation)
its not reabsorbed
define USG
estimate of urinary concentrating ability.
even at 33% there is still concentration of the urine
USG. the kidney can still concentrate
inability to concentrate urine causes____
polyuria
polyuria implies
loss of 66% mass
dog USG
1.001-1.060
cat USG
1.001- 1.080
bovine and horse USG
1.001 - 1.055
if the USG is above 1.017, does that indicate that the urine has some concentrating ability
yes, yes it does
in the dog and cat, what is the minimum dehydration concentrating capacity?
dog, 1.030
cat, 1.035
where are most proteins absorbed?
the PCT
what are the renal and extra renal DDxs of polyuria
renal (renal failure and pyelonephritis) extrarenal( diuresis, medullary washout
endocrine (diabetes and hyperadrenocortisim, pyometra
chemistry profile aspect that defines azotemia
inc BUN; inc creatinine
pre-renal azotemia is characterized by what pattern on a biochemical profile?
inc BUN; inc or dec Creatinine; inc specific gravity.
will also decrease GFR (check for NUM and CREA)
explain the DDXs for prerenal azotemia
can be either decreased blood flow or increased urea production
decreased blood flow can be caused by dehydration, shock, and low CO
increased urea production can be caused by upper GI bleed, high protein diet, endogenous protein catabolism, and in ruminants: low renal motility
what might be a normal USG range in a dehydrated Dog, Cat, horse and cattle?
Dog:1.030-1.060
cat: 1.040-1.080
horse and cattle: 1.025 - 1.045
prenreal azotemia can lead to ____urea production?
a: increased
B: decreased
a: increased
what specifically causes an increase in urea production in animals with pre renal azotemia
basically any source of amino acids like an upper GI bleed, high protein diet, decreased ruminal motility and endogenous protein catabolism
what are the sources of increased creatinine in an animal with pre renal azotemia?
increased muscle mass as is the case with greyhounds and males
neonatal foals with whose moms has dysfunctional placentas (usually clears after birth
what is the general biochemical pattern for renal azotemia
inc BUN
inc crea
dec SpGr
who is the posterchild for renal azotemia
old skinny cat.
renal azotemia results in a _____GFR, _____BUN, and ____CREA
increased all the way round
DDxs of renal azotemia
•Infectious Pyelonephritis, Leptospirosis •Toxins Ethylene glycol, drugs, grapes, Asiatic lilies,melamine,pigments (myoglobin, hemoglobin) •Hypoxia Decreased renal perfusion,infarction •Neoplasia Primaryor metastatic •Congenital Hypoplasiaor aplasia •Misc Hydronephrosis
T/F. an animal with azotemia and a really low USG means there is renal failre
false, it does not always mean this. it can mean electrolyte imbalances, endocrine function, or other drug effects
post renal azotemia basic biochemical pattern
inc BUN
inc. CREA
variable SpGr
DDxs dor post renal azotemia
urolithiasis in castrated males (FLUTD, goat urolithiasis)
uroabdomen (urolithiasis and trauma
T/F. Polyuria occurs before azometemia?
True (66% and 75% damage respectively)
azotemia and isosthenuria is
renal disease until proven otherwise
is it true that cats can still maintain some concentrating capacity with renal failure
Yes, because they live to make your life hard….makes them the best animals…they know humans are evil and deserve to be messed with.
what are prerenal causes of decreased BUN ONLY
decreased urea production as is the case with decreased blood to the liver (decreased dietary protein or a shunt; hepatic insufficiency)
intestinal loss in monogastics and horses (also exist to make you cry…damn suicidal animals horses are)
decreased water resorption to PCT in the renal tubules, means increased GFR and tubular flow (osmotic diuresis)
Do we care about decreased CREA?
hellz to the NO!
DDx fore pre- renal proteinuria
inc in small proteins in blood paraproteins (bence Jones) hemoglobinuria myoglobinuria post- colostral proteinuria
DDx’s for renal proteinuria
glomerular and tubular
glomerular:
hypoalbuminemia
damages to filtration
Tubular:
normal serum alb (maybe increased)
acute or congenital renal disease
defective PCT
loss of low molecular weight proteins
how does post renal proteinuria come about?
hemorrhagic/inflammatory
urine protein:creatinine ratio
Normal < 0.5
Borderline0.2 –0.5
Tubular or glomerular> 0.5
Glomerular >1.0
glomerular is more serious
general trends in the biochemical profile ass with renal failure
hyperCa (causes PU, renal mineralization, generally starts the kidney disease)
might see a very mild hypoCa ass with decreased vit C, diet and excretion in horses
hyperphosphatemia (decreased GFR and 75% loss at this point; low serum Ca leads to secondary hyperparathyroidism; horses lose P from the gut; may or may not happen in cattle)
metabolic acidosis in severe renal disease frim the loss of bicarb and secretion of H
hypochloremia seem particularily in cattle
the case of potassium ( normal in CRF; hypokalemia in uremic animals who are not eating; hypokalemic nephropathy; hyperkalemia (oliguria/anuria/ARF and or post renal condition)
uroabdomen and electrolyte imbalances (dogs, cats and newborn foals, look for inc KPP and dec NaCl
special note, in cattle hyperkalemia barely happens as any excess is excreted in the saliva
a peritoneal creatinine that is two times greater than serum creatinine is diagnostic for?
uroperitoneum
laboratory findings of acute renal failure
abrupt decrease in GFR
azotemia
hyperkalemia and acidemia
variable SpGr
oliguria/anuria
variable proteinuria and cellular casts
are chronic renal failure patients often hypertensive?
yes they are.
blood work for an animal with chronic renal failure
non regenerative anemia
dehydration azotemia hyperphasphatemia metabolic acidosis normokalemia to hypokalemia
urinalysis in a cat with chronic renal failure
oliguria and anuria and isosthenuria
what is glomerularnephritis and what can cause it?
glomerular damage from immune complex deposition and amyloid deposition
soft coated wheated terriers, especially those with coccidiomycosis that live in Arizona
glomerularnephritis allows for the passage of proteins past the membrane. this results in?
proteinuria and hypoproteinemia
lab findings of glomerularnephritis
hypoproteinemia
hypoalbuminemia.normoglobulinemia
mild to marked proteinuria
ecidence of renal insufficiency like axotenia and isosthenuria
define nephrotic syndrome
PLN leading to the formation of an abdominal transudate
will see hypoalbuminemia and hypercholesterolemia
alomerular disease, edema/abdominal effusion/hyper coagulable state from the loss of antithrombin
what is a biomarker?
a measurable sustance or its products used to predict the incidence of outcome or disease
what are some other biomarkers besides BUN and CREA used in renal disease
albumin
microalbuminuria (borderline patients)
cystatin C (the upcoming one)
SDMA (increases with 40% loss of renal tubular function (best to rule out renal failure in cats SDMA is)
