Electrolytes · Dysnatremia
Sodium Correction Calculator
Adrogue-Madias formula + Free Water Deficit
Adrogue HJ, Madias NE. N Engl J Med 2000;342:1493–1499, 1581–1589 · Verbalis JG, et al. Am J Med 2013;126(10 Suppl 1):S1–S42
How to use. Results are calculated automatically once all patient fields are filled in.
Switch tabs to choose hyponatremia/hypernatremia mode. Changing the fluid type or target updates the result immediately.
Patient Information
Sex / Age Group — determines TBW factor
Weight
kg
Current Serum Na
mEq/L
Correction Settings · Fluid Selection
Fluid to Use
ODS Risk Factors — select all that apply
Target ΔNa (24 hours)
Result · Adrogue-Madias
Fill in all patient fields to see the result calculated automatically.
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mEq/L per 1L fluid
Recommended Infusion Rate
— mL/hr
Total 24h Volume
— mL
Clinical Recommendation
Correction Settings · Free Water Deficit
Target Na
mEq/L
Correction Period
hr
Fluid to Use
Ongoing Fluid Loss Adjustment — fever, polyuria, diarrhea, etc.
Result · Free Water Deficit
Fill in all patient fields to see the result calculated automatically.
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L · Free Water Deficit
Recommended Infusion Rate
— mL/hr
Projected ΔNa/24h
−—
Clinical Recommendation
Sodium Correction Essentials (Adrogue-Madias, Verbalis et al.)
- Adrogue-Madias formula —
ΔNa = (Infusate Na − Serum Na) / (TBW + 1), the expected change in serum Na per liter of fluid. If KCl is added to the fluid, K is included too:(Na+K)infusate. - Hyponatremia correction limits — to prevent ODS,
≤8 mEq/L/24h(≤6 if high-risk),≤18 mEq/L/48h. High-risk factors: chronicity, hypokalemia, cirrhosis, alcohol use, malnutrition, Na<105. - Severe symptoms (seizures, obtundation, coma) — regardless of chronic vs. acute, give 3% NaCl 100 mL bolus over 10 min (up to 3 times) or 2 mL/kg. Target ΔNa +4–6 mEq/L within the first 6 hours.
- If overcorrected — actively relower with D5W or desmopressin (DDAVP) 2–4 μg IV to prevent ODS.
- Hypernatremia correction limits —
≤10 mEq/L/24hor≤0.5 mEq/L/hr. Acute onset (<24h) may be normalized within 24h; chronic cases should be corrected slowly due to cerebral edema risk. - Free water deficit —
FWD = TBW × (Nacurrent/Natarget − 1). Ongoing losses (insensible, sweat, polyuria) need separate replacement. - TBW factor — male 0.6 (0.5 if ≥65y), female 0.5 (0.45 if ≥65y). Adjust for obesity, pediatrics, or pregnancy.
- Limitations of this calculator — estimates assume a steady state. Accuracy may differ with ongoing losses, renal function/diuretics, or SIADH. Recheck serum Na every 2–4 hours.