Corrected Sodium Calculator

Corrected sodium	Range (mEq/L)	Meaning
Hyponatremia	< 135	True sodium is low even after correction
Normal range	135 – 145	Corrected sodium is within normal limits
Hypernatremia	> 145	True sodium is high — often a free-water deficit

Glucose (mg/dL)	Effect of correction
≤ 100	None — corrected sodium equals measured sodium
~100 – 150	Negligible (under ~1 mEq/L) — correction rarely needed
~150 – 400	Clinically meaningful — apply the correction
> 400	Large — the 1.6 vs 2.4 choice matters most here

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Walk-through

How to Use This Calculator

3 steps

1

Enter the measured sodium and glucose

Type the patient's measured serum sodium in mEq/L and serum glucose in mg/dL. These are the two values from the basic metabolic panel that the correction needs. The result updates instantly as you type.

2

Pick the correction factor for the headline

Choose Katz (1.6) or Hillier (2.4) from the dropdown. The selected factor sets which corrected value leads the result card — but both are always computed, so your choice never hides the other convention.

3

Read both results and the classification

The hero shows the corrected sodium for the selected factor, and the summary line names both Katz and Hillier. Open the Compare Factors tab to see them side by side, or the Interpretation tab to check the hypo/normal/hyper reference ranges.

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Reference

Formula & Methodology

3 formulas

Corrected sodium (general form)

Corrected Na = Na + factor * ((glucose - 100) / 100)

Add 'factor' mEq/L of sodium for every 100 mg/dL of glucose above 100. Sodium is in mEq/L and glucose in mg/dL. At a glucose of 100 the correction is zero, so the corrected value equals the measured value.

Katz factor (1973)

Corrected Na = Na + 1.6 * ((glucose - 100) / 100)

The classic default correction: 1.6 mEq/L of sodium per 100 mg/dL of glucose above 100. Equivalent to Na + 0.016 * (glucose - 100). Widely taught and used across most institutions.

Hillier factor (1999)

Corrected Na = Na + 2.4 * ((glucose - 100) / 100)

Hillier and colleagues measured a larger true sodium decrement, so this uses 2.4 mEq/L per 100 mg/dL of glucose above 100. Equivalent to Na + 0.024 * (glucose - 100), and it diverges most from Katz once glucose exceeds about 400 mg/dL.

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High YMYL

Trust, Methodology & Sources

Reviewed by Calculover Editorial Review · Updated 2026-07-22 · 3 sources

Editorial accountability

Author: Quinn Sumner - Editor

Owner: Quinn Sumner - Editorial owner

Reviewer: Calculover Editorial Review - Clinical-source review

Last reviewed: 2026-07-22

Last verified: 2026-07-22

Data effective: 2026-07-22

Methodology

The calculator implements the two published sodium corrections for hyperglycemia. Both use Corrected Na = measured Na + factor * ((glucose - 100) / 100), with factor = 1.6 (Katz, 1973) or 2.4 (Hillier et al., 1999). Sodium is in mEq/L and glucose in mg/dL. Both factors are computed on every calculation and the corrected value is classified against the standard 135-145 mEq/L reference range.

Assumption: The low measured sodium is dilutional from hyperglycemia; the patient may also have an independent sodium or free-water disorder that the correction helps unmask but does not diagnose.

Assumption: Sodium is entered in mEq/L and glucose in mg/dL, consistent with US laboratory reporting and the original Katz and Hillier derivations.

Limitations & guidance

The corrected sodium is a bedside estimate, not a measured laboratory value, and does not replace serum osmolality or a full assessment of volume status.

The 1.6 and 2.4 factors can give clinically different answers at high glucose (roughly above 400 mg/dL); the calculator reports both rather than selecting one, and the treating clinician decides which to apply.

The correction is only meaningful when glucose is elevated; at a normal glucose it does not change the sodium.

Professional guidance: This calculator is for education only and is not medical advice, diagnosis, or treatment. Corrected sodium is a screening estimate, not a diagnosis, and does not replace the judgment of a licensed clinician evaluating the full clinical picture.

Primary sources

Katz MA. Hyperglycemia-induced hyponatremia — calculation of expected serum sodium depression. N Engl J Med. 1973;289(16):843-844.

Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999;106(4):399-403.

MDCalc — Sodium Correction for Hyperglycemia

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Glossary

Key Terms Explained

7 terms

Corrected sodium The estimated serum sodium after accounting for the dilutional effect of high glucose — an approximation of what the sodium would be once glucose is normalized. Reported in mEq/L.

Hyperglycemia An elevated blood glucose level. It pulls water out of cells into the bloodstream, which dilutes the measured sodium and is the reason a correction is applied.

Pseudohyponatremia A measured sodium that looks low because of a physical or osmotic effect rather than a true sodium deficit. In hyperglycemia the low sodium is dilutional (translocational), and correcting for glucose reveals the true value.

Katz factor (1.6) The 1973 correction coefficient from Katz: add 1.6 mEq/L of sodium for every 100 mg/dL of glucose above 100. The most widely used default.

Hillier factor (2.4) The 1999 correction coefficient from Hillier et al.: add 2.4 mEq/L of sodium for every 100 mg/dL of glucose above 100. Better fits the true decrement, especially in severe hyperglycemia.

Osmotic shift The movement of water across cell membranes driven by a difference in solute concentration. High serum glucose creates an osmotic gradient that draws intracellular water into the blood, lowering sodium.

Free water Body water that is not accompanied by solute. Hyperglycemia effectively adds osmotically active glucose that redistributes free water, and tracking corrected sodium helps distinguish a dilutional picture from a true free-water deficit.

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Scenarios

Real-World Examples

3 worked examples

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Patient in diabetic ketoacidosis

Na 130, glucose 600 — DKA

Measured sodium 130 mEq/L Serum glucose 600 mg/dL

Glucose is 500 mg/dL above 100, so the correction adds 5 x 1.6 = 8 mEq/L for Katz and 5 x 2.4 = 12 for Hillier. Corrected sodium is about 138 (Katz) or 142 (Hillier) mEq/L — both in the normal range, showing the measured 130 was dilutional pseudohyponatremia, not true sodium loss.

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Patient with mild hyperglycemia

Na 138, glucose 300 — mild

Measured sodium 138 mEq/L Serum glucose 300 mg/dL

Glucose is 200 above 100, so the correction adds 2 x 1.6 = 3.2 (Katz) or 2 x 2.4 = 4.8 (Hillier). Corrected sodium is about 141.2 or 142.8 mEq/L — comfortably normal. At this moderate glucose the two factors differ by under 2 mEq/L, so the choice rarely changes management.

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Comparing the two factors at high glucose

Na 128, glucose 900 — factors diverge

Measured sodium 128 mEq/L Serum glucose 900 mg/dL

Glucose is 800 above 100. Katz adds 8 x 1.6 = 12.8 for a corrected 140.8; Hillier adds 8 x 2.4 = 19.2 for a corrected 147.2. The two conventions now disagree by more than 6 mEq/L — one reads normal, the other mild hypernatremia — which is exactly why the tool shows both instead of picking one.

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Deep Dive

Understanding the Corrected Sodium Calculator

3 chapters · 4 min read

When blood glucose is high, the measured serum sodium can look falsely low. This calculator applies the two published corrections — Katz (1.6) and Hillier (2.4) — to estimate the true sodium once glucose is accounted for, and shows both side by side so no single convention is silently assumed.

Why hyperglycemia lowers measured sodium

Glucose is an osmotically active solute. When it accumulates in the blood, it draws water out of cells and into the extracellular space, diluting the sodium that is measured there. The result is a low serum sodium that does not reflect a true deficit of body sodium — a dilutional or translocational hyponatremia, sometimes called pseudohyponatremia in this context.

The corrected sodium estimates what the sodium concentration would be if the glucose were brought back to normal. It does this by adding back the sodium that the excess water diluted: a fixed amount for every 100 mg/dL of glucose above 100.

The 1.6 versus 2.4 correction factor

Two conventions share the identical structure and differ only in the coefficient. Katz (1973) proposed adding 1.6 mEq/L of sodium per 100 mg/dL of glucose above 100, and this remains the most widely taught default. Hillier and colleagues (1999) measured the actual sodium change during controlled hyperglycemia and found the true decrement is larger — closer to 2.4 mEq/L per 100 mg/dL — particularly when glucose exceeds roughly 400 mg/dL.

At mild-to-moderate glucose elevations the two factors give nearly the same answer. As glucose climbs, they diverge, and the choice can shift the corrected value across a clinical threshold. Because practice varies and neither factor is universally 'correct', this calculator reports both and leaves the clinical judgment to the treating clinician.

Limits and how to use the result

The correction is a bedside estimate, not a measured value. It assumes the low sodium is purely dilutional from glucose; a patient can simultaneously have a true sodium disorder (real hyponatremia from vomiting or diuretics, or a free-water deficit), and the corrected number helps unmask that but does not diagnose it. The correction is only clinically meaningful once glucose is elevated — roughly above 150 to 200 mg/dL — and does nothing at a normal glucose. It is intended for education and clinical decision support and does not replace the treating clinician's assessment of osmolality, volume status, and the overall metabolic picture.

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Questions

Frequently Asked Questions

6 questions

Why do you correct sodium for hyperglycemia?+

High blood glucose draws water out of cells and into the bloodstream, diluting the measured sodium. This is called translocational or dilutional hyponatremia. The corrected sodium estimates what the sodium would be once glucose is normalized, so a low measured value is not mistaken for true sodium loss.

What is the difference between the 1.6 and 2.4 correction factors?+

The 1.6 factor comes from Katz (1973) and is the classic default: add 1.6 mEq/L of sodium for every 100 mg/dL of glucose above 100. The 2.4 factor comes from Hillier et al. (1999), who found the true sodium decrement is larger, especially when glucose exceeds about 400 mg/dL. This calculator shows both so you are not locked into one convention.

At what glucose level does sodium correction matter?+

The correction only becomes clinically meaningful once glucose is elevated — roughly above 150 to 200 mg/dL. Near-normal glucose produces a negligible change, and at a glucose of exactly 100 mg/dL the corrected sodium equals the measured sodium.

Is corrected sodium used in DKA?+

Yes. Diabetic ketoacidosis and hyperosmolar hyperglycemic state are the most common settings, because glucose is very high and the measured sodium often looks falsely low. Tracking the corrected sodium helps distinguish dilutional hyponatremia from a true free-water or sodium problem.

What units does the calculator expect?+

Sodium is entered in mEq/L and glucose in mg/dL, matching US laboratory reporting and the original Katz and Hillier formulas. If your glucose is reported in mmol/L, multiply by 18 to convert to mg/dL before entering it. The corrected sodium is returned in mEq/L.

Which correction factor should be used clinically?+

Clinical practice varies. The 1.6 factor remains the most widely taught and used, while some clinicians prefer the 2.4 factor for severe hyperglycemia based on Hillier's data. This tool intentionally reports both and does not choose for you — the treating clinician decides which to apply.

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