Functional acute renal failure ( prerenal oliguria ) and organic acute renal failure ( renal oliguria ) identification

    A urinary sediment : only appears when the function is often acute renal failure in a transparent and fine granular casts , and acute renal failure occurs when organic tubular epithelial cells , tubular degeneration of cells and a large number of coarse particles cell casts , but also a large number of free tubular epithelial cells.
    2 Urine - plasma osmolality ratio : normal or high urine osmolality when functional acute renal failure ( greater than 600 mOsm / l ) , urine - plasma osmolality ratio greater than 2:1 , and is urine osmolality close to plasma osmolality ( 300 mOsm / l ) when the quality of acute renal failure, both the ratio is less than 1:1.
    3 urinary sodium concentration: when functional acute renal failure, urinary sodium reabsorption function is not destroyed, and thus preserved sodium , urine sodium concentration less than 20 mEq / liter. When organic sodium reabsorption reduce acute renal failure , urinary sodium rises often more than 40 mEq / liter.
    4 Urine - plasma creatinine ratio : acute renal failure when the urine concentration of functional performance has not been destroyed, so the urine - often in plasma creatinine ratio greater than 40:1. When organic acute renal failure renal tubular necrosis . Urinary concentration function is damaged , urine - often less than plasma creatinine ratio of 10:1 .
    5 BUN - Creatinine Ratio : functional when the flow rate of decline in renal tubular acute renal failure , renal tubular reabsorption of filtered urea increased, creatinine excretion remains constant , therefore , BUN - Creatinine ratio greater than 20:1. When both organic acute renal failure often 10:1 ratio .
    6 hour phenol red excretion test : by a conventional method for phenol red test, but only one hour to collect urine specimens , the bladder with saline to reduce the error caused by residual urine . Phenol red excretion of the need for adequate renal blood flow and tubular secretion , excretion is minimal and therefore often expressed organic acute renal failure, such as phenol red excretion of more than 5% , there may be acute renal function decline , while not wholly impaired renal tubular function .