azotemia

what forces favor filtration?

blood pressure blood volume

what are the cutoffs that tell you if each species (cats, dogs, lg. animals, avians) are able to concentrate their urine?

cat > 1.035 dog>1.030 lg animals > 1.025 avian > 1.020

the ability to eliminate nitrogenous wastes is a measure of what function?

glomerular

what are urea/BUN and creatinine crude estimates of?

glomerular filtration rate (GFR)

what suggests a prerenal azotemia?

high urine specific gravity - primarily caused by decreased GFR (either due to dehydration or decreased cardiac output)

what kind of urine is produced when 2/3rds of the functioning nephrons are lost?

isosthenuric urine (or inadequately concentrated). fixed specific gravity 1.008-1.012

what causes a primary renal azotemia?

kidney malfunction, a multitude of conditions

is chronic renal disease reversible?

no

is hyposthenuria normal in dehydration?

no, then it is abnormal

is renal damage equivalent to renal failure?

no.

with chronic renal disease are the patients polyuric or oliguric/anuric?

polyuric, oliguria or anuria is more indicative of an acute situation

what typically causes hyposthenuria?

ADH problems

is it normal for there to be a slight hypersthenuria if dehydrated?

NO, may represent early renal failure

what does azotemia refer to?

a laboratory finding of increased concentration of urea and/or creatinine

what suggests prerenal azotemia?

- azotemia - adequately concentrated urine - signs of dehydration - lab data supporting dehydration - normal amounts of urine protein

what suggests GT imbalance?

- azotemia - maybe inadequately concentrated urine - proteinuria - increased fractional excretion of Na - maybe active urine sediment (casts)

causes of postrenal azotemia?

- blockage of urinary outflow - blockage of lower urinary tract - ruptured urinary bladder

how do chronic renal disease kidneys look on ultrasound? acute renal disease?

- chronic: small, fibrotic - acute: swollen, inflamed

what forces limit filtration?

- colloid osmotic (oncotic) pressure - small filtration pores - negative surface charges - pressures within tubule and renal interstitium

what causes pre-renal azotemia?

- decreased renal blood flow* - increased protein load

what conditions increase BUN only?

- endogenous protein breakdown - high protein meals - GI bleeding *

what things can cause a prerenal azotemia due to increased nitrogen load?

- increased protein catabolism (BUN only) -high protein meal (BUN only) - GI bleeding (again BUN only)

reduced blood flow lead to elevated BUN/creatinine and concentrated urine?

- less filtrated is presented to the tubule, decreasing GFR so less urea and creatinine are filtered - ADH is secreted to try to conserve water, leading to concentrated urine

what is the appearance of an anemia of chronic renal disease?

- normocytic, normochromic, nonregenerative anemia - a primary lack of renal erythropoietin production

what are the three different categories of azotemia?

- prerenal - primary renal - postrenal

what characteristics will you see with prerenal azotemia?

- reduced Glomerular blood flow - hypersthenuria (above critical value) - azotemia

what causes renal azotemia?

- tubular dysfunction (loss of concentration ability) - glomerulus dysfunction - acute/chronic failure

what are some other indicators of tubular damage?

- urine protein/Cr ratio of 1-3 - >3 casts/ LPF in urine - SDMA: symmetric dimethylarginine test

postrenal azotemia findings?

-anuria - large or ruptured urinary bladder - increased BUN and creatinine (large increases) - hyperkalemia - hyperphosphatemia - titration acidosis (increased anion gap, decreased TCO2) - USG variable

what abilities are lost in what order in renal failure?

1) the ability to produce a concentrate or dilute filtrate 2) ability to eliminate nitrogenous wastes 3) the ability to produce erythropoietin (move into a normocytic normochromic anemia)

if urine is adequately hypersthenuric we can assume what proportion of the nephrons are still functional?

1/3rd

what is uremia?

the manifestation in the patient. Depressed. maybe vomiting, anorexic, feeling bad

what does an increased fractional excretion of Na suggest?

tubular damage/loss - should normally be less than 1%

what ability to concentrate or dilute urine is a measure of what function?

tubular function

is a prerenal azotemia generally reversible?

yes