Free Water Deficit

Free water deficit, characterized by hypernatremia, is calculated based on age, sex, weight, and sodium. As always, if the result does not make sense check your work. Calculation is based on the formulas below:

Total body water = Wt(kg) * 0.6 (males) or 0.5 (females)

Use 0.5 in elderly males, 0.45 in elderly females

Free water deficit = (Sodium/140 - 1) * TBW

Free Water Deficit