Corrected sodium in hyperglycaemia
Sodium corrected for the dilutional effect of high glucose (Hillier factor 2.4)
Sources last checked: 2026-10-13
Corrected sodium in hyperglycaemia
Sodium corrected for the dilutional effect of high glucose (Hillier factor 2.4)
Hillier found the relationship non-linear: up to about 400 mg/dL (22 mmol/L) Katz's 1.6 fits well, above it a larger factor (≈ 4.0). The 2.4 factor is the overall average.
Interpretation
| < 135 — hyponatraemia | True (hypotonic) hyponatraemia persists after correcting for glucose. |
|---|---|
| 135–145 — normal range | Low measured sodium is explained by hyperglycaemia. |
| > 145 — hypernatraemia | Free-water deficit is masked by hyperglycaemia; sodium will rise as glucose falls. |
What is the Corrected sodium in hyperglycaemia?
In hyperglycaemia, glucose draws water out of cells and dilutes serum sodium. The corrected sodium estimates what the sodium would be at normal glucose. Hillier, Abbott and Barrett (1999) measured the effect experimentally and found an average fall of 2.4 mmol/L sodium per 100 mg/dL (5.55 mmol/L) rise in glucose, larger than Katz's classic 1.6.
When to use it
- Diabetic ketoacidosis and hyperosmolar hyperglycaemic state
- Interpreting a low sodium in a patient with marked hyperglycaemia
- Anticipating the sodium change as glucose is lowered
When not to use it
- Pseudohyponatraemia from hyperlipidaemia or paraproteinaemia (indirect ion-selective electrodes)
- Hyponatraemia from other osmoles such as mannitol
How it is calculated
Corrected Na = measured Na + 2.4 × (glucose [mg/dL] − 100) ÷ 100 (no correction below 100 mg/dL) Glucose mmol/L × 18.016 = mg/dL (equivalently ≈ 0.43 mmol/L Na per 1 mmol/L glucose above 5.55)
Clinical pearls and limitations
- Hillier found the relationship non-linear: up to about 400 mg/dL (22 mmol/L) Katz's 1.6 fits well, above it a larger factor (≈ 4.0). The 2.4 factor is the overall average.
- A normal or high corrected sodium during DKA/HHS signals a free-water deficit.
- Up to about 22 mmol/L glucose the 1.6 factor fits; above it the effect is larger, which the 2.4 average partly captures.
- As glucose falls, the measured sodium is expected to rise.
Frequently asked questions
What is the Hillier correction for sodium?
Add 2.4 mmol/L to the measured sodium for every 100 mg/dL (5.55 mmol/L) of glucose above 100 mg/dL.
Should I use 1.6 or 2.4 as the correction factor?
Hillier's experiment found 2.4 overall; 1.6 fits better at glucose up to about 400 mg/dL (22 mmol/L). Many guidelines and teaching materials quote either.
How do I use glucose in mmol/L?
Select mmol/L; it is converted with × 18.016. Each mmol/L of glucose above 5.55 adds about 0.43 mmol/L sodium.
Evidence and guidelines
Have a follow-up question?
Medelix answers clinical questions from current guidelines and studies — every statement with its source.
Ask Medelix about the Corrected sodium in hyperglycaemiaRelated calculators
Embed this calculatorFree to use on your website, intranet or teaching page. Copy the code below.
<iframe src="https://medelix.ai/en/embed/corrected-sodium" title="Corrected sodium in hyperglycaemia – Medelix" width="100%" height="620" style="border:0;max-width:720px" loading="lazy"></iframe>
<p><a href="https://medelix.ai/en/calculators/corrected-sodium-hyperglycaemia">Corrected sodium in hyperglycaemia calculator by Medelix</a></p>For healthcare professionals and medical students. These tools support, and do not replace, clinical judgement. Always check results against the original source and your local protocols.