Eleven cases of nonoliguric acute renal failure, all but one following burns, as well as 14 cases of postburn oliguric acute renal failure, have been treated at the US Army Surgical Research Unit since 1960. Mild azotemia not attributed to parenchymal renal failure occurred in an additional ten burned patients. The urine sodium concentration exceeded 20 mEq/liter in eight of 11 patients with oliguric acute renal failure, whereas only one of nine nonoliguric patients had a urine sodium concentration above 20 mEq/liter. Thus, a low urine sodium concentration is not helpful in distinguishing functional renal insufficiency from parenchymal renal failure unless oliguria is present.
Vertel RM, Knochel JP. Nonoliguric Acute Renal Failure. JAMA. 1967;200(7):598–602. doi:10.1001/jama.1967.03120200076012