title: Fractional excretion of sodium as a guide to volume depletion during recovery from acute renal failure.
abstract: Fractional excretion of filtered sodium (FENa) is typically elevated (greater than 3%) in acute tubular necrosis and decreased (less than 1%) with volume depletion. We describe a patient who developed acute tubular necrosis with a FENa of 13%. Four weeks later, he was still oliguric but had also become volume-depleted. FENa was 0.4% to 0.8%, considerably lower than FENa's measured in eight nonvolume-depleted patients in acute renal failure. Vigorous intravenous fluid therapy in this patient produced a prompt increase in urine volume and improvement in renal function. We conclude the following: (1) a marked decrease in FENa in a patient with acute tubular necrosis should suggest the development of a superimposed sodium-retaining state such as volume depletion, and (2) severe volume depletion may delay or mask recovery from acute tubular necrosis.
mesh_terms: D058186:Acute Kidney Injury / Q000209:etiology / Q000503:physiopathology / Q000628:therapy / Q000652:urine*; D005110:Extracellular Space / Q000502:physiology*; D005440:Fluid Therapy; D006801:Humans; D007683:Kidney Tubular Necrosis, Acute / Q000150:complications / Q000503:physiopathology / Q000652:urine; D008297:Male; D008875:Middle Aged; D012964:Sodium / Q000652:urine*; D014563:Urodynamics
chemical_list: D012964:Sodium