Corrected Sodium Calculator
Correct a serum sodium result for a high blood glucose. When glucose is very high it pulls water into the bloodstream and dilutes the sodium, so the measured value understates the true (corrected) sodium. Enter the measured sodium and glucose to see the corrected sodium by both the widely used Katz factor of 1.6 and the Hillier factor of 2.4, which is more accurate at very high glucose levels.
About corrected sodium
Correcting sodium for glucose reveals the true sodium status behind the dilution caused by hyperglycaemia, which matters in diabetic emergencies. Sources: Katz MA, New England Journal of Medicine 1973; Hillier TA et al., American Journal of Medicine 1999.
Frequently asked questions
What is the corrected sodium formula?
The common Katz formula is: corrected sodium = measured sodium + 1.6 × (glucose − 100) ÷ 100, with glucose in mg/dL. The Hillier formula uses a factor of 2.4 instead of 1.6 and fits the data better when glucose is above about 400 mg/dL. Both add roughly 1.6–2.4 mmol/L of sodium for every 100 mg/dL that glucose is above 100.
Why correct sodium at all?
A high glucose draws water out of cells into the blood, diluting the sodium so the measured value looks lower than the body’s true sodium. Correcting reveals whether the patient is actually sodium-depleted, normal or high once the glucose effect is removed — which changes how hyponatraemia in diabetic emergencies such as DKA or HHS is interpreted and treated. With the values this page opens on — a measured sodium of 130 mmol/L at a glucose of 600 mg/dL — the Katz correction gives 138.0 mmol/L and the Hillier correction 142.0, so the apparent hyponatraemia is largely an artefact of the glucose. The correction changes the interpretation rather than the treatment on its own; fluid and insulin therapy still follows the whole clinical picture.
Should I use the 1.6 or 2.4 factor?
The 1.6 (Katz) factor is the traditional, most widely taught version and is fine for moderate elevations. The 2.4 (Hillier) factor is more accurate when glucose is markedly raised, roughly above 400 mg/dL. This calculator shows both so you can see the range; many clinicians quote the 1.6 value and keep the 2.4 value in mind at very high glucose.
My glucose is in mmol/L — what do I do?
Multiply mmol/L by 18 to get mg/dL (so 20 mmol/L ≈ 360 mg/dL), then enter that value. Sodium is the same number in both systems. The correction only matters when glucose is clearly raised; near-normal glucose changes the sodium by a negligible amount.
What is a normal sodium?
A typical reference range for serum sodium is about 135–145 mmol/L, though it varies by laboratory. The corrected value is what you compare against this range in the setting of hyperglycaemia. This calculator is an educational reference, not medical advice.
This is a reference tool, not a diagnosis or medical advice. Results depend on the laboratory, assay and clinical context, and reference intervals vary between labs and by age and sex — always read your result against the range printed on your own report and discuss it with a qualified healthcare professional.
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