How to use the fractional excretion of sodium calculator
Find the fraction of filtered sodium the kidneys excrete, to help tell causes of kidney injury. Enter urine sodium, plasma creatinine, plasma sodium, urine creatinine in the fields above; the fractional excretion of sodium is computed instantly and plotted on the chart so you can see how the answer changes.
Common searches this calculator answers include “FENa”, “fractional excretion sodium”, “kidney sodium excretion”, “calculate fractional excretion of sodium”, “find fractional excretion of sodium”.
Formula
Variables
- una — Urine sodium (mmol/L)
- pcr — Plasma creatinine (mg/dL)
- pna — Plasma sodium (mmol/L)
- ucr — Urine creatinine (mg/dL)
Worked example
With urine sodium = 20 mmol/L, plasma creatinine = 1.0 mg/dL, plasma sodium = 140 mmol/L, urine creatinine = 100 mg/dL, the calculator gives fractional excretion of sodium ≈ 0.1428571 %.
Frequently asked questions
What is the fractional excretion of sodium calculator used for?
Find the fraction of filtered sodium the kidneys excrete, to help tell causes of kidney injury. It helps with questions such as “FENa”, “fractional excretion sodium”, “kidney sodium excretion”.
What is the formula for the fractional excretion of sodium calculation?
Fractional excretion of sodium (%) = una × pcr / (pna × ucr) × 100. Here una is urine sodium (mmol/L), pcr is plasma creatinine (mg/dL), pna is plasma sodium (mmol/L), ucr is urine creatinine (mg/dL).
What inputs do I need for the fractional excretion of sodium calculator?
You need urine sodium in mmol/L, plasma creatinine in mg/dL, plasma sodium in mmol/L, urine creatinine in mg/dL. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use the fractional excretion of sodium calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the fractional excretion of sodium result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.