Home › Clinical Tools › FENa

🫘 Fractional Excretion of Sodium (FENa)

UseDifferentiate pre-renal from intrinsic (ATN) acute kidney injury.

Loading calculator…

SourceEspinel CH. JAMA 1976

Runs locally in your browser (no PHI uploaded). For licensed clinicians — not a substitute for clinical judgement.
Stored on this device for revisit reminders

This-shift next steps

After scoring: open the scene pack, peer scores, and the matching pathway. Local reference — no HIS write.

Scene next step
📋Renal function / dosingOpen scene pack →
Related scores
Matching pathway
🧭hyperkOpen pathway →
Score + version; reference only — not a substitute for care · no HIS write

Paste the link in Slack, Teams, X, or LinkedIn — the preview image comes from this page’s Open Graph card.

Methodology · worked example, guidelines & full notes
Clinical takeaway

Unreliable after diuretics — use FEUrea instead.

When to use

Differentiate pre-renal from intrinsic (ATN) acute kidney injury.

How it works

FENa = (UNa × PCr) / (PNa × UCr) × 100. < 1% pre-renal; > 2% intrinsic/ATN.

Key points

  • Unreliable after diuretics — use FEUrea instead.
  • Also unreliable in CKD, contrast nephropathy and glomerulonephritis.
  • Interpret with the clinical picture and urine microscopy.

References

Worked calculation

The values below come from this tool's own example placeholders and are computed server-side with the formula shown on this page, so the arithmetic can be checked quickly. It demonstrates how to substitute values only — it is not clinical advice and not a real case.

Urine sodium20 mmol/L
Plasma sodium140 mmol/L
Urine creatinine100 mg/dL
Plasma creatinine2.0 mg/dL

→FENa0.29%

  • Interpretation：< 1% — suggests pre-renal
  • Formula：FENa = (UNa·PCr)/(PNa·UCr) × 100
Verification & sources · governance
FAQ

Frequently asked questions

What are the limits and cautions when using Fractional Excretion of Sodium (FENa)?
For licensed clinicians and clinical researchers. Interpret results with history, investigations and local protocols; not a diagnosis or prescription, and not a substitute for multidisciplinary decision-making or local guidelines.
Does Fractional Excretion of Sodium (FENa) upload patient data? Where is it calculated?
Calculation runs locally in the browser; inputs and results are not uploaded. For licensed clinicians only; interpret with history, investigations and local protocols — not a diagnosis or prescription.
How is Fractional Excretion of Sodium (FENa) calculated in practice? Can you show a worked example?
Inputs: Urine sodium 20 mmol/L, Plasma sodium 140 mmol/L, Urine creatinine 100 mg/dL, Plasma creatinine 2.0 mg/dL → Result: FENa 0.29 %（Interpretation: < 1% — suggests pre-renal, Formula: FENa = (UNa·PCr)/(PNa·UCr) × 100）
Related tools

Other tools