Prerenal azotemia - urine osmolality is increased (above 500 mOsm/kg), a BUN to creatinine ratio of greater than 20, a fractional excretion of sodium less than 1%
Intrinsic renal failure - urine osmolality is decreased (below 350 mOsm/kg), a BUN to creatinine ratio of less than 20, fractional excretion of sodium greater than 2%, and (muddy brown epithelial/granular casts in ATN)
Postrenal azotemia - urine osmolality is decreased (below 350 mOsm/kg), and other lab values often vary
submitted by โshak360(19)
There are three types of AKI