title: Urinary diagnostic indices in acute renal failure: a prospective study.
abstract: A prospective analysis of the value of urinary diagnostic indices in ascertaining the cause of acute renal failure was undertaken. Our results show that in the setting of acute oliguria a diagnosis of potentially reversible prerenal azotemia is likely with urine osmolality greater than 500 mosm/kg H2O, urine sodium concentration less than 20 meq/litre, urine/plasma urea nitrogen ratio greater than 8, and urine/plasma creatinine ratio greater than 40. Conversely, a urine osmolality less than 350 mosm/kg, urine sodium concentration greater than 40 meq/liter, urine/plasma urea nitrogen ratio less than 3, and urine/plasma creatinine ratio less than 20 suggest acute tubular necrosis. A significant number of oliguric patients will not have urinary indices that fall within these guidelines. In this setting, urine sodium concentration divided by the urine-to-plasma creatinine ratio (the renal failure index) and the fractional excretion of filtered sodium provide a reliable means of differentiating reversible prerenal azotemia from acute tubular necrosis.
mesh_terms: D058186:Acute Kidney Injury / Q000175:diagnosis / Q000652:urine*; D000368:Aged; D003404:Creatinine / Q000378:metabolism; D005260:Female; D006801:Humans; D007683:Kidney Tubular Necrosis, Acute / Q000652:urine; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011446:Prospective Studies; D012964:Sodium / Q000652:urine; D014508:Urea / Q000378:metabolism; D014511:Uremia / Q000652:urine
chemical_list: D014508:Urea; D012964:Sodium; D003404:Creatinine