Fractional excretion of sodium

Na filtered through glomerulus vs Na ended up in the urine

• A measure of tubular resorption of Na.
  • Lower = less excreted = more renal sodium retention
  • < 1% = Pre-renal AKI

  • 1% = re-absorption not working = more likely ATN - Acute tubular necrosis

• It is a calculation based on the concentrations of sodium and creatinine in the blood and urine.

Fractional Excretion of Sodium (FENa)