free_water_deficit: Free Water Deficit in Hypernatremia

In cliot: Clinical Indices and Outcomes Tools

Free Water Deficit in Hypernatremia

Description

Calculates the estimated free water deficit in patients with hypernatremia. The formula relies on Total Body Water (TBW), which is estimated based on the patient's age, sex, and weight. This calculation helps guide fluid replacement therapy to lower serum sodium levels safely.

Usage

free_water_deficit(current_na, weight_kg, age, sex, target_na = 140)

Arguments

current_na	Numeric. Current serum sodium level in mEq/L.
weight_kg	Numeric. Patient weight in kilograms.
age	Numeric. Patient age in years. Used to determine the TBW fraction (Children: 0.6; Adults 18-64: M=0.6/F=0.5; Elderly >=65: M=0.5/F=0.45).
sex	String. Patient sex ("Male" or "Female").
target_na	Numeric. The desired target serum sodium level. Defaults to 140 mEq/L.

Value

A list containing:

Free_Water_Deficit_L	The estimated volume of free water required to correct the sodium to the target level.
Total_Body_Water_L	The estimated Total Body Water used in the calculation.
TBW_Fraction_Used	The coefficient used to calculate TBW based on demographics.

References

Adrogué HJ, Madias NE. Hypernatremia. N Engl J Med. 2000;342(20):1493-1499. doi:10.1056/NEJM200005183422006

Examples

# Example 1: Adult Male
# Na 160, Wt 75kg, Age 40 (TBW factor 0.6)
# TBW = 45L. Deficit = 45 * ((160/140) - 1) = 6.4 L
free_water_deficit(160, 75, 40, "male")

# Example 2: Elderly Female
# Na 155, Wt 60kg, Age 75 (TBW factor 0.45)
# TBW = 27L. Deficit = 27 * ((155/140) - 1) = 2.9 L
free_water_deficit(155, 60, 75, "female")

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