Health & Fitness
FENa Calculator (Fractional Excretion of Sodium)
Differentiate prerenal from intrinsic acute kidney injury using the fractional excretion of sodium.
Preparing your result…
What this calculator does
Calculates FENa Calculator (Fractional Excretion of Sodium) using the formula verified against the cited source.
What your result means
An estimate from the inputs you enter, within the scope stated below — not advice.
Formula
FENa (%) = (Una × Pcr) ÷ (Pna × Ucr) × 100
The step-by-step working for your own numbers appears with the result above and in the PDF report.
Frequently asked questions
Symbols and assumptions
- Inputs
- The values entered in the fields above
- • FENa%=100×(urine sodium×plasma creatinine)/(plasma sodium×urine creatinine). Pair sodium units and creatinine units consistently between urine and plasma; denominator must be nonzero.
Sources and review
Reviewed 2026-10-18 · Next review 2027-04-18
- • Use temporally corresponding urine/plasma samples. FENa alone does not distinguish all AKI causes; diuretics, CKD and other conditions affect interpretation. Do not apply a universal diagnostic label from a single cutoff.
Important limitation
This is an educational estimate based only on the values and formula shown. Verify current rates, rules, units, and professional standards before relying on the result. It is not personalized financial or investment advice.
Quick reference
| Scenario | Urine sodium (mEq/L) | Plasma sodium (mEq/L) | Urine creatinine (mg/dL) | FENa |
|---|---|---|---|---|
| Worked example | 20 | 140 | 60 | 0.3571 % |
| Half the amounts | 10 | 100 | 30 | 0.2667 % |
| Double the amounts | 40 | 170 | 120 | 0.5882 % |
Need the full picture? Get the detailed PDF report with charts, tables, formulas and working steps.
Reviewed 2026-10-18 · Next review 2027-04-18
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