calculate_fena: Fractional Excretion of Sodium (FENa)

In cliot: Clinical Indices and Outcomes Tools

Fractional Excretion of Sodium (FENa)

Description

Calculates the Fractional Excretion of Sodium (FENa) to help differentiate between prerenal azotemia and acute tubular necrosis (ATN) in patients with oliguric acute kidney injury.

Usage

calculate_fena(serum_sodium, serum_creatinine, urine_sodium, urine_creatinine)

Arguments

serum_sodium	Numeric. Serum Sodium level in mEq/L or mmol/L.
serum_creatinine	Numeric. Serum Creatinine level in mg/dL or umol/L (must use consistent units with urine creatinine).
urine_sodium	Numeric. Urine Sodium level in mEq/L or mmol/L.
urine_creatinine	Numeric. Urine Creatinine level in mg/dL or umol/L (must use consistent units with serum creatinine).

Value

A list containing:

FENa_Percent	The calculated FENa percentage.
Etiology	Interpretation (Prerenal < 1%, Intrinsic > 2%).

References

Espinel CH. The FeNa test. Use in the differential diagnosis of acute renal failure. JAMA. 1976;236(16):1795-1797. doi:10.1001/jama.1976.03270170035022

Examples

# Example 1: Prerenal (Dehydration)
# SNa 140, SCr 1.5, UNa 10, UCr 100
# FENa = (10 * 1.5) / (140 * 100) * 100 = 0.11%
calculate_fena(140, 1.5, 10, 100)

# Example 2: Intrinsic (ATN)
# SNa 135, SCr 2.0, UNa 40, UCr 40
# FENa = (40 * 2.0) / (135 * 40) * 100 = 1.48% (Indeterminate range, close to ATN)
calculate_fena(135, 2.0, 40, 40)

cliot documentation built on Dec. 1, 2025, 1:06 a.m.