Clinical decision support
Fractional excretion of sodium (FENa)
Calculate FENa to help differentiate prerenal, intrinsic renal, and postrenal causes of azotemia in dogs and cats. Enter paired urine and plasma electrolytes with creatinine. Educational decision-support tool only.
Safety checks
- This tool supports calculation and education only.
- It does not diagnose, prescribe, or replace clinical judgment.
- FENa is influenced by medications, diet, and hydration status.
- Always use paired samples collected near the same time.
- Creatinine values must use identical units.
Basis and limits
- Formula: FENa (%) = (Urine Na × Plasma Cr) / (Plasma Na × Urine Cr) × 100.
- Prerenal: FENa < 1% suggests intact tubular sodium reabsorption.
- Intrinsic renal: FENa > 2% suggests tubular damage or diuretic effect.
- Postrenal: FENa may be variable; obstruction can cause either pattern.
- Scope: this tool provides arithmetic support. It does not replace full renal workup.
Formula audit trail
Calculation steps will appear here for verification.