Hypervolemic hyponatremia due to cirrhosis is caused by an increment in total body water (TBW) in excess of an increase in total exchangeable sodium (Na) and potassium (K). Therefore, therapy is aimed at treating not only the hyponatremia but there is an additional requirement to treat the volume overload.

Correction of cirrhosis-associated hyponatremia can be achieved by ensuring that the negative water (HO) balance is in excess of the negative Na and K balance. This therapeutic approach can be attained by administering intravenous 3% sodium chloride (NaCl) and furosemide.

Presently, there is no quantitative method for predicting the volume of IV 3% NaCl required to be infused in conjunction with furosemide that satisfies this therapeutic goal. Therefore, based on the empirical relationship between the plasma Na concentration and exchangeable Na, K, and TBW, a new formula is derived to calculate the volume of IV 3% NaCl required to raise the plasma Na concentration ([Na]) to a targeted level ([Na]) by attaining the desired amount of negative Na, K and HO balance.

This new equation is the first quantitative approach for treating hypervolemic hyponatremia by attaining a negative HO balance in excess of negative Na and K balance. This formula is particularly useful in the treatment of cirrhosis-associated hyponatremia where there are limited therapeutic options.