Question

Mrs Jones weighs 170#. Her serum sodium in 159 mEq/L What is her free water deficit? Show your work.

Answer 1

CLINICAL SHORTCUT FOR FINDING FREE WATER DEFICIT

SUBSTRACT THE DIFFERENCE BETWEEN THE PATIENTS (NA+) AND 140

DIVIDE BY 3

here patient's sodium is 159

159 - 140 =19

19 divide by 3 =6.3

The total number of sodium molecules in patients body is constant ,and rise in serum [Na+ ] is due to concentration due to water loss

how much water should we add to reduce theseum sodium back to normal (for this patient it is 6.3 litters)

note-140 is constant in this calculation