Calculate free water deficit and correction rate for hypernatremia
Please enter sodium between 130 and 200 mEq/L.
Please enter target sodium between 135 and 145 mEq/L.
Please enter weight between 1 and 200 kg.
TBW Fractions Used:
Young male: 0.60 | Elderly male: 0.50
Young female: 0.50 | Elderly female: 0.45
✓ Free Water Deficit Results
⚠ Monitoring: Check serum sodium every 2–4 hours during active correction. Avoid over-rapid correction (risk of cerebral oedema). Add 30–40 mL/hr to the calculated rate for ongoing insensible losses.
Hypernatremia Severity Reference
Na (mEq/L)
Severity
Symptoms
Action
145–149
Mild
Thirst, malaise
Oral rehydration
150–159
Moderate
Weakness, lethargy
Oral or IV rehydration
160–169
Severe
Confusion, seizure risk
IV D5W, slow correction
≥170
Critical
Coma, herniation risk
ICU, careful IV D5W
Formulas
TBW (L) = TBW_fraction × Weight (kg)
(Young male: 0.60 | Elderly male: 0.50 | Young female: 0.50 | Elderly female: 0.45)
Free Water Deficit (L) = TBW × [(Na_current / Na_target) − 1]
Correction rate (chronic): ≤0.5 mEq/L/hr; max 8–10 mEq/L per 24h
Correction rate (acute, <48h): up to 1–2 mEq/L/hr
