Free Water Deficit Calculator
Calculate Free Water Deficit using serum sodium, body weight, age group, and sex. This calculator estimates the amount of free water required to correct hypernatremia.
Calculation Result
Formula
Total Body Water (TBW) Factor
| Patient | TBW Factor |
|---|---|
| Adult Male | 0.60 |
| Adult Female | 0.50 |
| Elderly Male | 0.50 |
| Elderly Female | 0.45 |
Interpretation
| Serum Sodium | Interpretation |
|---|---|
| ≤145 mEq/L | No significant free water deficit. |
| 146–155 mEq/L | Mild to moderate free water deficit. |
| >155 mEq/L | Severe free water deficit. Gradual correction under medical supervision is recommended. |
Clinical Use
The Free Water Deficit Calculator estimates the amount of water required to correct hypernatremia. It is commonly used in nephrology, intensive care, and emergency medicine. The calculated value should be used together with clinical assessment, ongoing fluid losses, and treatment goals.
Frequently Asked Questions (FAQ)
What is Free Water Deficit?
Free Water Deficit is the estimated volume of water needed to restore serum sodium concentration toward the normal range in patients with hypernatremia.
When is this calculator used?
It is used in patients with hypernatremia due to dehydration, diabetes insipidus, excessive water loss, or inadequate water intake.
Should hypernatremia be corrected rapidly?
No. Chronic hypernatremia should generally be corrected gradually to reduce the risk of cerebral edema. Treatment decisions should always follow current clinical guidelines.
Can this calculator replace medical judgment?
No. This calculator is intended for educational and clinical support purposes only. Patient management should always be based on professional medical assessment.
Disclaimer
This calculator is intended for educational and laboratory reference purposes only. It should not replace professional medical advice, diagnosis, or treatment.
References
- Adrogué HJ, Madias NE. Hypernatremia. New England Journal of Medicine.
- KDIGO Clinical Practice Guidelines.
- Tietz Textbook of Clinical Chemistry and Molecular Diagnostics.