Sodium Correction Rate Calculator for Hypo- and Hypernatremia

The sodium correction rate calculator uses the patient's weight, serum sodium concentration, the aimed increase of serum sodium, and the chosen fluid's parameters to find the serum sodium change per liter and the rate of the sodium replacement fluid flow.

Read on to see what sodium replacement formula we used. You'll also probably find our water deficit, sodium deficit, sodium correction for hyperglycemia, or fractional excretion of sodium (FENa) calculators useful.

We try our best to make our Omni Calculators as precise and reliable as possible. However, this tool can never replace a professional doctor's assessment. All information on this website is for informational purposes only and is not intended to serve as a substitute for medical consultation. Always consult your results with a health care provider.

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

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

where:

• fluid_sodium – 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);
• fluid_potassium – Concentration of potassium in the fluid you're planning to use. Most fluids don't contain potassium, but e.g. lactate ringer contains 4 mEq/L. You need to put that value separately in the corresponding field;
• serum_Na – Measured concentration of sodium in the blood serum;
• TBW – 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, with the option of adding the level of potassium in the fluid into the equation:

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

where:

• aimed_change – 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 and development of osmotic demyelination, and result in brain damage or death.
Experts recommend the sodium correction not to 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 health care provider, as this calculator cannot replace clinical judgement 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. If the chosen fluid contains potassium, enter its concentration. According to the table mentioned above, it's 4 mEq/L (or mmol/L) in lactated Ringer's, and 5 mEq/L (mmol/L) in Ringer's acetate.

6. 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 are equal to millimoles per liter (mmol/L).

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