Water Deficit in Hypernatremia
Calculate the free water deficit in hypernatremia and the safe correction rate using the Adrogue-Madias formula.
Patient Parameters
Male 0.50 × wt, Female 0.45 × wt instead of standard 0.60/0.50
Normal range: 135–145 mEq/L. Hypernatremia: > 145 mEq/L.
Enter patient parameters and click
Calculate Water Deficit
Results
Free Water Deficit
— L
— mL
Formula Breakdown
Total body water (TBW)—
TBW coefficient—
Na ratio (current / target)—
Safe Correction Timeline
Clinical note: This estimate covers the static deficit only. Add ongoing insensible and urinary losses. Recheck serum sodium every 4–6 hours and adjust the rate accordingly. Not a substitute for clinical judgment.
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Summary
Calculate the free water deficit in hypernatremia and the safe correction rate using the Adrogue-Madias formula.
How it works
- Enter the patient weight in kilograms.
- Select the biological sex to determine the total body water (TBW) coefficient.
- Enter the current serum sodium level (mEq/L).
- Set the target sodium (default 140 mEq/L).
- The calculator applies the Adrogue-Madias formula: Deficit = TBW × ((Na_current / Na_target) − 1).
- Read the water deficit volume and the safe correction plan (max 10–12 mEq/L per 24 h).
Use cases
- Estimating free water replacement volume for hypernatremic patients in the ICU.
- Planning IV fluid orders for patients with severe hypernatremia.
- Cross-checking bedside nursing calculations against a formula reference.
- Medical student and resident learning tool for electrolyte physiology.
- Emergency department management of hyperosmolar states.
- Teaching the impact of sex and age on total body water fraction.
Frequently Asked Questions
Last updated: 2026-07-26 ·
Reviewed by Nham Vu