Free Water Deficit Calculator
Estimate the water deficit in liters for patients based on serum sodium levels and body weight.
What is Water Deficit?
Water deficit represents the amount of water required to return a patient’s serum sodium concentration to normal levels. It is used in cases of hypernatremia (elevated sodium levels) and guides medical professionals in treatment planning. The calculation considers serum sodium levels, body weight, and a correction factor based on the patient’s demographic (male, female, or child).
Formula:
Water Deficit = [(Serum Sodium / 140) – 1] × Correction Factor × Body Weight
where Correction Factor reflects water distribution in the body:
0.6 for males, 0.5 for females, and 0.7 for children.
How to Use the Free Water Deficit Calculator
Follow these steps to calculate free water deficit:
- Enter the patient’s current serum sodium level in mEq/L. Ensure the value is above the normal range (135–145 mEq/L) since calculation is primarily for hypernatremia cases.
- Provide the patient’s body weight in kilograms (kg). This is a crucial factor in determining total body water.
- Select the appropriate correction factor. Use 0.6 for males, 0.5 for females, and 0.7 for children.
- Click the “Calculate” button to obtain the water deficit in liters. Results will display immediately along with the calculation process for better understanding.
The result indicates the amount of free water (in liters) needed to correct the sodium imbalance. Always validate with a healthcare professional before taking action.