Free water deficit calculator

Free Water Deficit

Free Water Deficit in Hypernatremia

Parameter	Value
Weight (kg)
Sex	1 Male (TBW = 0.6)   Female (TBW = 0.5)
Elderly/Child	1 No   Yes (TBW −0.1)
Current Serum Sodium (mEq/L)
Free Water Deficit	L

Notes

Formula: FWD = TBW × [(Current Na / 140) – 1] TBW = Weight × correction factor (Male 0.6, Female 0.5; reduce by 0.1 for elderly) Correction rate: Do not decrease Na by >10–12 mEq/L per 24 hours to avoid cerebral edema. Adrogué HJ, Madias NE. Hypernatremia. N Engl J Med. 2000;342(20):1493-1499. PMID 10816188.