Calculate water deficit for 50 kg male with Na=160 meq-
Ans. is 'b' i.e., 2.8 L half normal saline Estimation of the water deficit o The water deficit in the hypernatremic patient can be estimated from the following formula. Water deficit = Current TBW x Serum (Na) (__________ 140 -1) o TBW refers to the estimated total body water, which is normally about 60 and 50 percent of lean body weight in younger men and women, respectively, and about 50 and 45 percent of lean body weight in elderly men and women respectively. Total body water for males = weight x .6 Total body water for females = weight x 5 o Of note, if the serum sodium is 141 meq/L and TBW is approximately 50 percent of lean body weight, then the water deficit is about 3 mL/kg. o This provides the rationale for the estimation, mentioned above, that a net positive balance of3 mL of electrolyte free water per kilogram of lean body weight will lower the serum sodium. 160- 140 140 x.6 x 50 = 2.8 Litres
2.8 L hypertonic saline
2.8 L half normal saline
1.5 L 5% dextrose in water
1.5 L 10% dextrose in water
Fluid & Electrolyte