renal emergency-medicine
Fractional Excretion of Sodium (FENa)
Differentiates pre-renal AKI from intrinsic renal AKI. FENa <1% suggests pre-renal cause; >2% suggests intrinsic renal disease.
Score interpretation
FENa <1% — Pre-renal AKI likely
→ Volume depletion or low cardiac output; IV fluid challenge; assess fluid status; may be misleading in contrast nephropathy or early obstruction
FENa 1-2% — Indeterminate
→ Consider clinical context; early ATN, myoglobinuria, or contrast nephropathy can give low FENa
FENa >2% — Intrinsic renal AKI likely
→ ATN most common; consider GN, interstitial nephritis; avoid nephrotoxins; nephrology review
Interpretation bands for the FENa. Apply clinical judgement and local guidance.
References
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
Drugs
- Mannitol (Osmotic Diuretic — Renal/Neurological) · Acute Oliguric Renal Failure / Raised ICP
- Thiopental Sodium · Barbiturate Induction Agent
- Sodium Bicarbonate · Alkalising Agent / Electrolyte
- Sodium Chloride 3% (Hypertonic Saline) · Hypertonic Electrolyte Solution — ICP/Hyponatraemia Management
- Sodium Nitroprusside · Vasodilator — Nitric Oxide Donor (IV)
- Dantrolene sodium · Skeletal muscle relaxant (RyR1 inhibitor)
Pathways
- Hyperkalaemia Management · UK Kidney Association Guidelines 2020; NICE CKD Guidelines
- Rhabdomyolysis · Renal Association 2018; UpToDate 2024
- Hypocalcaemia (Adult) · Society for Endocrinology
- SIADH (Endocrine Perspective) · European Hyponatraemia Guidelines 2014
- Hepatorenal Syndrome · EASL 2018; ICA 2015
- Acute Kidney Injury (AKI) · KDIGO 2012 / NICE AKI 2019
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.