Sodium Correction Rate Calculator for Hypo- and Hypernatremia

The sodium correction rate calculator uses the Adrogue-Madias formula, as it is the one most widely used sodium correction formula in the prediction of serum sodium change:

change in serum sodium = (fluid_sodium - serum_sodium) / (TBW + 1)

where:

• fluid_sodium is the concentration of sodium in the fluid you're planning to use. The values provided here are based on this table of the composition of commonly used crystalloids by the National Institute for Health and Care Excellence (NICE).
• serum_Na is the measured concentration of sodium in the blood serum.
• TBW is the total body water. We calculate this by multiplying the patient's weight by the age/sex coordinate, which equals 60% for children and adult males, 50% for adult females and elderly males, and 45% for elderly females. See the total body water calculator.

Then, to calculate the sodium correction rate, we use the inverse of the previous calculation:

correction flow rate = 1000 × aimed_change × (TBW + 1) / (fluid_sodium - serum_sodium),

where:

• aimed_change is the aimed serum sodium change per hour. As there is a risk of overcorrection.

Keep in mind that rapid sodium correction may lead to cerebral edema or the development of osmotic demyelination, which may, in turn, result in brain damage or death.

Experts recommend that the sodium correction should not exceed 8 mmol/L/day. Remaining within this daily range, the initial correction rate in patients with severe symptoms can be 1 - 2 mEq/L/hr for several hours.

You should always check the results and the current guidelines with another healthcare provider, as the sodium replacement rate calculator cannot replace clinical judgment and medical assessment.

1. Choose the patient's age/sex group from the five options given in the first line: child, adult female, adult male, elderly female, and elderly male.

2. Type in the patient's weight in the preferred unit.

3. Enter the measured serum sodium level. If your results are in mmol/L, type in these values – in the case of sodium, they are equal to those in mEq/L.

4. Choose the kind of sodium replacement fluid you're planning to use.

5. The predicted serum sodium change per liter of administered replacement fluid is given in the second to last field in milliequivalents per liter (mEq/L), which is equal to millimoles per liter (mmol/L).

6. The calculated sodium correction rate is presented in the last field in milliliters per hour (ml/h).