Intrinsic Acute Kidney Injury Flashcards
What is creatinine and how is it used?
a molecule released at a steady state from muscle, filtered by kidney
instead state, allows tracking of kidney function in individual
needs to be converted to GFR via formula
if there is a rise of 0.3 mg/dL, signifies AKI
stages of chronic kidney disease
stage 1 - GFR >= 90 mL/min, proteinuria
stage 2 - GFR between 60 and 89 mL/min
stage 3 - GFR between 30 and 59 mL/min
stage 4 - GFR between 15 and 29 mL/min
stage 5 - GFR less than 15 mL/min
definition of acute renal failure
an abrupt (within 48 hours) reduction in kidney function
absolute increase in serum creatining of either >= 0.3 mg/dL or a percentage increase of >= 50%
a reduction in UOP (documented oliguria of < 0.5 mL/kg per h for > 6 hours
AKIN creatinine criteria for acute kidney injury
stage 1 - increase in SCr of 1.5-2 or >= 0.3 mg/dL
stage 2 - increase in serum creatinine of 2-3 fold
stage 3 - increase in Scr > 3 fold or baseline Cr. > 4 with an acute rise > 0.5 mg/dL
AKIN urin output criteria for acute kidney injury
stage 1 - < 0.5 mL/kg per h for 6 h
stage 2 - < 0.5 mL/kg per h for 12 h
stage 3 - < 0.3 mL/kg per h for 24h, or anuria for 12 h
obstructive uropathy
acute renal failure occurring with obstruction of both urinary outflow tracts or the outflow tract of a single kidney
etiologies include - prostatic or cervical neoplasia, neurogenic bladder, intraluminal obstruction (crystals, stones blood)
clinical findings of obstructive uropathy
may or may not be oliguric
hyperkalemia
treatment of obstructive uropathy
relief of obstruction
recovery of renal function may be inversely related to length of time obstruction persists
recognize the possibility of a diuretic phase
urinary indices for prerenal injury
UOsm > 500
UNa < 20
FENa < 1
urinary indices for ATN
UOsm < 350
UNa > 40
FENa > 1
urinary indices for AGN
UOsm 300-500+
UNa < 40
FENa < 1
urinary indices for obstructive uropathy
UOsm 300-500
UNa > 40
FENa > 1
What is the most common cause of ischemic acute renal failure?
severe and sustained prerenal azotemia
Describe the current state of predictive tests for extent of renal injury.
creatinine is not sensitive for renal injury
no biomarkers like cardiology yet
urine sediment is helpful but takes skill
normotensive ischemic AKI
normally the kidney maintains blood flow through a wide range of pressures
however in patients with imparied autoregulation, the GFR falls below normal values while the mean arterial pressure remains within the normal range
