Urinary Diagnostic Indices in Acute Renal Failure

Publisher Website
Google Scholar
Abstract
A prospective analysis of the value of urinary diagnostic indices in ascertaining the cause of acute renal failure was undertaken. In the setting of acute oliguria a diagnosis of potentially reversible prerenal azotemia is likely with urine osmolality > 500 mosmol/kg H2O, urine Na concentration < 20 meq/l, urine/plasma urea N ratio > 8 and urine/plasma creatinine ratio > 40. Conversely, a urine osmolality < 350 mosmol/kg, urine Na concentration > 40 meq/l, urine/plasma urea nitrogen ratio < 3 and urine/plasma creatinine ratio < 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 Na concentration divided by the urine-to-plasma creatinine ratio (the renal failure index) and fractional excretion of filtered Na provide a reliable means of differentiating reversible prerenal azotemia from acute tubular necrosis.