Fractional Excretion of Sodium (FENa)
Determines if renal failure is due to pre-renal, post-renal, or intrinsic renal pathology.
| Prerenal | Intrinsic Renal | Postrenal | UNa (mmol/L) | <20 | >40 | >40 | FENa | <1% | >1% | >4% |
|---|
Prerenal: Anything that causes decreased effective renal perfusion: Hypovolemia, CHF, Renal Artery Stenosis, Sepsis, etc. Remember, contrast-induced nephropathy will often look pre-renal.
Intrinsic Renal: ATN, AIN, Glomerulonephritides, etc
Postrenal: Obstruction (BPH, bladder stone, bilateral ureter obstruction)
Fractional Excretion of Sodium (FENa) = (PCr * UNa ) / (PNa x UCr) %
Posted in: Critical Care • Nephrology • Renal
