Sodium Correction Calculator

1 What is the Sodium Correction Calculator?

The Sodium Correction Calculator estimates the sodium deficit in a hyponatraemic child and the volume of 3% saline needed for symptomatic correction. It uses Sodium deficit (mEq) = (Goal Na − Measured Na) × weight × 0.6, where 0.6 represents the total body water fraction, alongside a symptomatic bolus dose of 3% saline at 6 mL/kg. The tool pairs these calculations with explicit correction-rate safety limits to reduce the risk of overly rapid sodium correction.

2 When to use it

Quantifying the sodium deficit in a child with symptomatic or asymptomatic hyponatraemia to guide replacement fluid planning
Determining the volume of 3% hypertonic saline needed for a child who is seizing or comatose from severe hyponatraemia
Planning a safe, gradual correction rate to avoid osmotic demyelination syndrome
Supporting the diagnostic work-up of hyponatraemia (SIADH, hypovolaemia, cerebral salt wasting, water intoxication, adrenal insufficiency)
Guiding fluid restriction decisions when SIADH is suspected as the underlying cause

3 Formula & method

Na deficit = (Na_goal − Na_meas) × wt × 0.6 (0.6 = total body water fraction). The symptomatic bolus is calculated as 3% saline at 6 mL/kg, described in the app as '3% saline 6 mL/kg over 10–60 min → ↑ Na by ≈5 mEq/L (use only if seizing/comatose)'. The app's safety guidance states slow correction should run at 0.5 mEq/L/hr with a maximum of approximately 10 mEq/L per 24 hours, and that the symptomatic dose is '3% NaCl 4–6 mL/kg (max 100 mL) IV over 10–30 min — repeat to control symptoms.'

4 Frequently asked questions

How is the sodium deficit calculated?

The app uses Na deficit (mEq) = (Goal Sodium − Measured Sodium) × weight (kg) × 0.6, with 0.6 representing total body water as a fraction of weight.

How fast can sodium be corrected?

Per the app's safety guidance, the slow/standard correction rate is 0.5 mEq/L/hr, with a maximum of about 10 mEq/L per 24 hours.

When is 3% saline used, and how much?

The app reserves 3% saline for symptomatic hyponatraemia (a seizing or comatose patient), dosed at 4–6 mL/kg (max 100 mL) over 10–60 minutes, expected to raise sodium by approximately 5 mEq/L.

What is the risk of correcting sodium too quickly?

The app warns that over-rapid correction can cause osmotic demyelination syndrome (ODS).

What causes should be investigated in hyponatraemia?

The app lists SIADH, hypovolaemia, cerebral salt wasting, water intoxication, and adrenal insufficiency, noting that water restriction is appropriate if SIADH is diagnosed.

5 Related tools

For qualified clinicians. This page and the PediAid app are a clinical aid only. Calculations and reference data must be verified against the patient's clinical context, the source guideline and your local protocols before any treatment decision is made.