renal disorders Flashcards
How are the causes of renal dysfunction catergorized?
causes of kidney dysfunction are divided into 3 categories based on the mechanism of injury; prerenal, intrarenal, & postrenal
What are prerenal injuries related to?
decrease in blood flow & perfusion
What are intrarenal injuries related to?
secondary to actual injuries to the kidney itself
What are postrenal injuries related to?
related to obstruction of urine outflow from the kidneys
list possible causes of prerenal injury
- hypotension
- shock
- diarrhea (severe)
- vomiting (severe)
- bleeding/hemorrhage
- diuretics
- diabetes insipidus
- burns
- HF/MI
- cirrhosis
- sepsis
list possible causes of intrarenal injury
- vasculitis
- venous occlusion
- pre-eclampsia
- acute tubular necrosis
- multiple myeloma
- hypercalcemia
- IV contrast dyes
- pyelonephritis
- certain meds: NSAIDS, ACEI, heavy metals
- transfusion reaction
- rhabdomyolysis
list possible causes of post renal injury
- renal calculi
- enlarged prostate
- cancer
- diabetes
- functional obstruction due to drugs
- blood clot
- trauma
What is the most common cause of acute kidney injury?
acute tubular necrosis (ATN)
What occurs when acute tubular necrosis is present?
damage to renal tubules causing cells to slough into the tubular lumen and lumen becomes blocked
- fluid unable to go thru lumen; decreased urine formation ; ultimately no urine if untreated
- blocked lumen exacerbates ischemic injury to cells & causes additional intrarenal injury
What are possible causes acute tubular necrosis?
post - ischemia (all causes of severe pre-renal disease)
nephrotoxins
is acute tubular necrosis permanant or reversible?
permanent injury if not reversed
What 3 things were mentioned to cause nephrotoxicity?
aminoglycosides
IV contrast dye
multiple myeloma
What is creatinine clearance (100-150cc/min) in prerenal azotemia vs ATN?
prerenal azotemia - 15-80cc/min
ATN - less than 5-10cc/min
What is urine sodium (10-20mEq/L) in prerenal azotemia vs. ATN?
prerenal azotemia - less than 10 mEq/L
ATN - greater than 20 mEq/L
What is specific gravity(1.005-1.025) in prerenal azotemia vs ATN?
prerenal azotemia - greater than 1.015
ATN - 1.010 fixed
What is urine osmolality (200-1200mOsm/kg) in prerenal azotemia vs ATN?
prerenal azotemia - concentrated >450mOsm/kg
ATN - isomotic = 300mOsm/kg
What is serum BUN (10-20)/ creatinine in prerenal azotemia vs ATN?
prerenal azotemia - greater than 15:1
ATN - 10:1 fixed
What is the UA like in prerenal azotemia vs. ATN?
prerenal azotemia - normal
ATN - red/qhite cells, casts & epithelial cells
What is oliguria?
urine output <400 ml/day
What is anuria?
urine output < 30-40 ml/day
What are the 4 stages of an AKI?
initial onset
oliguria
late diuretic
recovery
What happens in the initial onset phase of an AKI?
- 0-2 days
- initial insult to point when BUN/Cr rise and/or urine output drops
What happens in the oliguria phase of an AKI?
- 1-2 days to 6-8 weeks
- drop in GFR, rention of urea, potassium, sulfate & creatinine
- decrease urine output & edema
What happens in the late diuretic phase of an AKI?
- 2-8 days
- begins with a slow, gradual increase in urine output, then high output (up to 10L in 24 hr)