RenalNephrology

Fractional Excretion of Sodium

Differentiates pre-renal from intrinsic renal AKI. FENa < 1% = pre-renal. Invalid on diuretics — use FEUrea instead.

Urine sodium

mmol/L

Serum sodium

mmol/L

Urine creatinine

µmol/L

Serum creatinine

µmol/L

Reference: Miller TR et al. Ann Intern Med 1978

Medical Disclaimer: This calculator is a clinical decision support tool for qualified healthcare professionals. It does not replace clinical judgement. Always interpret results in the full clinical context. Reference: Miller TR et al. Ann Intern Med 1978.

More Nephrology Calculators

RenalCockcroft-Gault

Estimates CrCl for drug dosing. Standard formula for renal dose adjustment (not for CKD staging).

RenalAnion Gap

Detects unmeasured anions in metabolic acidosis. Corrected for hypoalbuminaemia. Normal: 3–11 mEq/L.

RenaleGFR (MDRD)

Estimates glomerular filtration rate from creatinine, age, and sex for CKD staging and monitoring.

RenalFEUrea

Differentiates pre-renal from intrinsic renal AKI, particularly useful when diuretics preclude interpretation of FENa.