Renal function

Fractional excretion of Na (FENa)

Pre-renal vs intrinsic AKI distinction. Not reliable on diuretics — use FEUrea.

AKIpre-renal

Required inputs

  • Urine Na mEq/L
  • Serum Na mEq/L
  • Urine creatinine
  • Serum creatinine

Equation or source

Espinel CH. JAMA 1976;236:579.

Provenance and release status

Equation / algorithm
Pre-renal vs intrinsic AKI distinction. Not reliable on diuretics — use FEUrea.
Formula version
fena-v1
Tool version
2.4.0
Clinical risk class
B. CLINICAL DECISION-SUPPORT CALCULATOR
Release status
Verified
Source status
Direct primary or authoritative source identifier resolved
Clinical review status
Independent formula verification completed; clinical review date not documented
Clinical review date
Clinical review date not yet documented

Assumptions

  • Entered values and units are accurate and apply to the population described by the cited source.
  • The published equation or rule is being used without a patient-specific clinical adjustment.

Important limitations

  • The result does not replace clinical assessment or establish a diagnosis.
  • Performance outside the source population may differ.
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