Corrected Sodium Calculator

1 What is the Corrected Sodium Calculator?

The Corrected Sodium Calculator adjusts measured serum sodium for the dilutional effect of hyperglycaemia, helping clinicians tell true hyponatraemia apart from a falsely low sodium caused by high glucose. It applies the standard correction, Corrected Na = Measured Na + 1.6 × ((Glucose − 100) / 100), and also displays an alternate calculation using a factor of 2.4 that the app attributes to Hillier, American Journal of Medicine 1999, for glucose above 400 mg/dL. The tool then interprets the corrected value against normal, low, and high sodium bands.

2 When to use it

Evaluating a hyperglycaemic patient (e.g. diabetic ketoacidosis) with a low measured sodium to determine whether true hyponatraemia is present
Distinguishing dilutional (glucose-driven) hyponatraemia from a hyponatraemia that will persist even after glucose is treated
Monitoring corrected sodium trends during DKA management, since a rising corrected sodium as glucose falls can signal cerebral oedema risk
Deciding whether further hyponatraemia work-up (volume status, urine osmolality, urine sodium) is needed after correcting for glucose
Comparing the standard correction factor against the alternate higher-glucose factor in cases of severe hyperglycaemia

3 Formula & method

Corrected Na = Na + 1.6 × ((Glucose − 100) / 100), the standard result shown by the app. Alongside it, the app displays a 'Hillier formula (× 2.4) — for glucose > 400 mg/dL': Na + 2.4 × ((Glucose − 100) / 100), noting it 'may better reflect true Na in severe hyperglycaemia.' The app then bands the standard corrected value as: below 135 mEq/L (hyponatraemia after correction), 135–145 mEq/L (normal — 'purely dilutional from the hyperglycaemia'), and above 145 mEq/L (hypernatraemia after correction, flagged as a cerebral oedema red flag in DKA if rising as glucose falls).

Hillier, Am J Med 1999

4 Frequently asked questions

What formula does the Corrected Sodium Calculator use?

Corrected Na = Measured Na + 1.6 × ((Glucose in mg/dL − 100) / 100).

Why does the app also show a factor of 2.4?

The app attributes a 2.4 correction factor to Hillier, American Journal of Medicine 1999, noting it may better reflect true sodium in severe hyperglycaemia above 400 mg/dL, and displays it as an additional result alongside the standard 1.6 calculation.

What does a normal corrected sodium mean if the measured sodium was low?

The app explains that if the corrected value falls between 135–145 mEq/L, the original low sodium reading was purely dilutional from hyperglycaemia and should resolve as glucose is treated.

Why does corrected sodium matter in DKA?

The app flags that a rising or high corrected sodium as glucose falls during DKA treatment is a red flag for cerebral oedema, warranting slower fluid replacement and hourly neuro-observations.

What inputs are needed?

Measured serum sodium (mEq/L) and glucose (mg/dL).

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.