This formula will provide the expected rate of change of plasma sodium concentration for a given infusion tonicity and a given urine composition
TBW = Sex * Weight
VolDelta = VolInfusate - VolUrine
NaChange = ((VolInfusate * (NaInfusate + KInfusate)) - (VolUrine * (NaUrine + KUrine)) - (VolDelta * NaSerum)) / (TBW + VolDelta)
- 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.
- Medscape renal calculators
*Please note: this calculator is intended for educational usage only and should never be used to replace clinical decision making by a qualified practitioner.