* Required


TBW = Sex * Weight
VolDelta = VolInfusate – VolUrine
NaChange = ((VolInfusate * (NaInfusate + KInfusate)) – (VolUrine * (NaUrine + KUrine)) – (VolDelta * NaSerum)) / (TBW + VolDelta)


  • Equation parameters such as Sex have two or more discrete values that may be used in the calculation. The numbers in the parentheses, e.g. (0.6), represent the values that will be used.


  1. Barsoum NR, Levine BS. Current prescriptions for the correction of hyponatraemia and hypernatraemia: are they too simple?. Nephrol Dial Transplant. 2002 Jul;17(7):1176-80.
  2. Management Strategies and Outcomes for Hyponatremia in Cirrhosis in the Hyponatremia Registry. Sigal SH, Amin A, Chiodo JA rd Sanyal A, Can J Gastroenterol Hepatol 2018 Sept 27: 1579508

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