What is corrected sodium?

Corrected sodium is a calculated estimate that adjusts the measured sodium for the water shift associated with hyperglycaemia. The measured sodium remains the laboratory result. The corrected value is not a second measurement and should not be treated as exact. Use it as an interpretation aid alongside glucose, osmolality or tonicity, fluid balance and serial laboratory results.

What is the corrected sodium formula for hyperglycaemia?

Using glucose in mg/dL, Katz estimates corrected sodium as measured sodium + 1.6 × ((glucose − 100) ÷ 100); Hillier uses 2.4 instead of 1.6. MedMaths can accept glucose in mmol/L or mg/dL and normalises the arithmetic internally before applying the selected correction factor. The correction is an estimate for hyperglycaemia, not a direct sodium measurement or a universal treatment target.

Why does high glucose lower the measured sodium?

High extracellular glucose pulls water out of cells, increasing extracellular water and diluting the measured sodium concentration. This is a real osmotic water shift, sometimes described as translocational or hypertonic hyponatraemia. It is different from pseudohyponatraemia, which is a laboratory measurement artefact associated with some indirect measurement methods.

Which corrected sodium formula should I use — Katz or Hillier?

Use the method specified by the relevant guideline, local protocol or clinical reference. Katz 1.6 is the classic correction; Hillier 2.4 is an alternative overall empirical estimate. The two methods can diverge as glucose rises, so MedMaths shows both estimates after calculation and highlights the method you selected. Neither correction factor should be treated as a universal biological constant for every patient.

Why do Katz and Hillier give different corrected sodium results?

They use different sodium correction factors for the same rise in glucose: 1.6 for Katz and 2.4 for Hillier. The difference is small at modest hyperglycaemia and becomes larger as glucose rises further above 100 mg/dL. Seeing both estimates makes the formula uncertainty visible instead of hiding it behind one result.

What happens to corrected sodium at very high glucose?

Fixed correction factors become increasingly approximate at very high glucose concentrations. Hillier and colleagues found the sodium-glucose relationship was not perfectly linear in their experimental study, particularly above about 400 mg/dL (22.2 mmol/L). That is why MedMaths shows a high-glucose warning rather than presenting either factor as exact in severe hyperglycaemia.

Can I enter glucose in mmol/L or mg/dL?

Yes. Select the unit shown on the laboratory report before entering the glucose value. The calculation is normalised internally to the conventional 100 mg/dL glucose reference, which is about 5.55 mmol/L. A unit mismatch can create a very large error, so check the selected glucose unit before calculating.

Should sodium and glucose be from the same blood test or time point?

Use sodium and glucose from the same clinical time point where possible. Both values can change quickly during treatment of severe hyperglycaemia. Combining values from different times can make the calculated estimate misleading.

Is corrected sodium the same as serum osmolality or tonicity?

No. Corrected sodium estimates a glucose-adjusted sodium concentration; osmolality and tonicity answer different clinical questions. If osmolality is the clinical question, use measured laboratory data and an appropriate osmolality calculation rather than treating corrected sodium as an osmolality result.

Can corrected sodium determine which IV fluid to give?

No. Corrected sodium can support interpretation, but it does not select a fluid type or infusion rate by itself. Hyperglycaemic-crisis management depends on the full clinical picture, serial sodium and osmolality, glucose, potassium, renal function, haemodynamics and the relevant treatment protocol.

Corrected Sodium Calculator

Lab corrections

What is the estimated corrected sodium?

Enter the measured sodium and blood glucose, then choose the glucose unit and correction formula.

Measured sodium (Na⁺)*mmol/L

Enter the measured serum sodium from the laboratory report.

Glucose unit

Choose the unit shown on the laboratory report.

Blood glucose*mmol/L

Enter the measured blood glucose in the selected unit.

Correction formula

Katz 1.6 is the classic correction. Hillier 2.4 is an alternative overall empirical estimate from a 1999 experimental study.

Katz uses a correction factor of 1.6 mmol/L per 100 mg/dL (5.55 mmol/L) rise above the equation's 100 mg/dL reference point. That reference is not a diagnostic hyperglycaemia threshold.

Use the laboratory values exactly as reported

Corrected sodium is an estimate used in hyperglycaemia, when extracellular glucose shifts water out of cells and lowers the measured sodium concentration. Use sodium and glucose from the same clinical time point and select the glucose unit shown on the laboratory report.

Simple answer

How is sodium corrected for hyperglycaemia?

Start with the measured sodium, then add a glucose-dependent correction. MedMaths lets you choose either the Katz 1.6 factor or the Hillier 2.4 factor.

Example: Measured sodium 128 mmol/L with glucose 500 mg/dL (about 27.8 mmol/L) gives 134.4 mmol/L with Katz or 137.6 mmol/L with Hillier.

The conventional equation reference is 100 mg/dL ≈ 5.55 mmol/L. It is an arithmetic reference point, not a diagnostic threshold for hyperglycaemia. The corrected value is a calculated estimate, not a replacement laboratory measurement.

What does corrected sodium mean?

Corrected sodium estimates the sodium concentration after mathematically normalising glucose to about 100 mg/dL while assuming body water, sodium and potassium are otherwise unchanged. The measured sodium remains the laboratory result; the corrected value is an interpretation aid, not a literal prediction of the next laboratory sodium during treatment.

Katz 1.6 or Hillier 2.4?

Katz 1.6

The classic correction. The 2024 adult hyperglycaemic-crisis consensus still describes an approximately 1.6 mmol/L sodium rise for each 100 mg/dL fall in glucose during HHS treatment.

Hillier 2.4

An alternative overall empirical estimate from the 1999 Hillier study. The same study also found the relationship became non-linear at very high glucose.

Use the method named by the relevant guideline, local protocol or clinical reference. If no method is specified, comparing both estimates makes the uncertainty visible rather than implying one factor is universally correct.

Use corrected sodium as an interpretation aid

Hyperglycaemic emergencies require assessment of glucose, fluid balance, electrolytes and the wider clinical picture. A correction formula can support interpretation, but it does not replace direct laboratory measurements, serial sodium/osmolality trends or local management guidance.

Clinical use and safety

When to use this calculator — and its limits

The arithmetic can be correct while the clinical decision is still wrong. These boundaries show what the calculator can and cannot establish.

When to use

Use when hyperglycaemia is lowering the measured serum sodium and you want a calculated estimate of the sodium concentration after accounting for the glucose-related transcellular water shift.
Enter measured sodium and glucose from the same clinical time point where possible, then select the correction method required by your source or local practice.
Use the result as an interpretation aid alongside serial measured sodium, glucose, osmolality/tonicity, fluid balance and the wider hyperglycaemic-crisis assessment.

Key limitations

Corrected sodium is an estimate based on normalising glucose to about 100 mg/dL while body water, sodium and potassium are otherwise assumed unchanged; it is not a second laboratory measurement or an exact prediction of the patient's sodium after treatment.
Katz 1.6 is the classic theoretical estimate. Hillier's 1999 experiment in six healthy subjects found an overall factor of 2.4 and a non-linear relationship at very high glucose concentrations; neither factor is a universal biological constant for every patient.
At very high glucose concentrations, fixed linear correction factors become increasingly approximate. Hillier found that the relationship changed above about 400 mg/dL in that experiment.
The 2024 international adult hyperglycaemic-crisis consensus describes an approximately 1.6 mmol/L sodium rise for each 100 mg/dL fall in glucose during HHS treatment, but management depends on serial sodium and osmolality trends rather than a single corrected value.
The formula addresses hyperglycaemia-related translocational sodium lowering. If pseudohyponatraemia is suspected because of marked lipids/proteins or a discordant osmolality picture, verify the sodium measurement method or a direct ISE result; applying a glucose correction does not repair an indirect-ISE measurement artefact.

What MedMaths does not decide

Which correction factor a particular protocol or laboratory should use.
Whether true sodium deficit or excess, pseudohyponatraemia, DKA, HHS or another diagnosis is present.
Fluid composition, fluid rate, insulin treatment, potassium/electrolyte replacement or the safe rate of change in sodium or osmolality.
Whether treatment should be changed because of one calculated corrected-sodium result.

Evidence and method checks

Hyperglycemia-induced hyponatremia — calculation of expected serum sodium depression — New England Journal of Medicine / PubMed
Hyponatremia: evaluating the correction factor for hyperglycemia — American Journal of Medicine / PubMed
Hyperglycemic Crises in Adults With Diabetes: A Consensus Report — ADA / EASD / JBDS / AACE / DTS
Comparison of commonly used equations for sodium adjustment in hyperglycaemia — Pathology / RCPA
The Corrected Serum Sodium Concentration in Hyperglycemic Crises: Computation and Clinical Applications — Frontiers in Medicine / PubMed Central
Pseudohyponatremia: Mechanism, Diagnosis, Clinical Associations and Management — Journal of Clinical Medicine / PubMed Central
Diabetes Care in the Hospital: Standards of Care in Diabetes—2026 — American Diabetes Association

Formula logic and known-value examples are checked as part of the MedMaths review process.

See how MedMaths checks calculator methods →

Measured sodium

This is the laboratory sodium concentration before any mathematical adjustment for hyperglycaemia.

Corrected sodium

This is an estimate of the sodium concentration after accounting for the dilutional effect associated with elevated glucose.

Formula, examples and learning guide

Review how glucose changes measured sodium, Katz vs Hillier, worked examples, unit conversion, common mistakes, clinical context and FAQs.

How corrected sodium works

Start with the measured serum sodium from the laboratory report.
Enter the blood glucose from the same clinical time point where possible.
Select the glucose unit exactly as reported: mmol/L or mg/dL.
Choose the correction method: Katz 1.6 or Hillier 2.4.
Calculate how far glucose is above the formula's reference glucose, then add the corresponding sodium correction.
Interpret the result as a calculated estimate alongside measured sodium, osmolality/tonicity, fluid status and the wider hyperglycaemic-crisis assessment.

Katz and Hillier correction formulas

Katz method — conventional-unit form

In simple words

For each 100 mg/dL (approximately 5.55 mmol/L) that glucose is above the 100 mg/dL reference, the Katz method adds about 1.6 mmol/L to the measured sodium.

Measured Na⁺: = laboratory serum sodium in mmol/L
Glucose: = blood glucose in mg/dL for this conventional-unit form; MedMaths accepts mmol/L and converts internally
100 mg/dL: = approximately 5.55 mmol/L, the glucose reference used by this calculator
1.6: = Katz sodium correction factor in mmol/L per glucose increment

Hillier overall correction

Corrected Na⁺ = measured Na⁺ + 2.4 × [(glucose mg/dL − 100) ÷ 100]

Hillier and colleagues studied six healthy subjects and found 2.4 mmol/L per 100 mg/dL was the better overall estimate. In that experiment, 1.6 fit reasonably up to about 400 mg/dL, while a factor around 4.0 fit the higher-glucose portion better. MedMaths keeps 4.0 as study context only rather than inventing a universal third pathway.

When glucose is reported in mg/dL

MedMaths normalises the glucose internally to mg/dL before calculating so mmol/L and mg/dL inputs follow the same arithmetic path. The familiar conventional-unit shorthand uses 100 mg/dL as the reference and applies the selected correction factor for each additional 100 mg/dL.

Where the Katz and Hillier corrections came from

Katz, 1973: Murray A. Katz published the classic sodium-glucose relationship in the New England Journal of Medicine. The paper described the estimate that serum sodium falls by about 1.6 mmol/L for each 100 mg/dL rise in glucose. That 1.6 factor became the conventional correction used for decades.

Hillier, Abbott and Barrett, 1999: the later American Journal of Medicine study tested the relationship experimentally in six healthy subjects. Glucose was raised above 600 mg/dL and sodium and glucose were measured repeatedly as glucose changed. The mean overall sodium change was 2.4 mmol/L per 100 mg/dL. In the piecewise analysis, 1.6 worked reasonably up to about 400 mg/dL while a factor around 4.0 fit the higher-glucose portion better; that 4.0 observation is study context, not a validated universal high-glucose rule.

That is why MedMaths presents 1.6 as the classic Katz estimate and 2.4 as Hillier's overall experimental estimate. Neither value should be treated as an exact biological constant for every patient. The 2024 international adult hyperglycaemic-crisis consensus also describes an approximately 1.6 mmol/L rise in sodium for each 100 mg/dL fall in glucose during HHS treatment, while emphasising serial laboratory and clinical reassessment.

Formula source: Murray A. Katz → Teresa A. Hillier →

Corrected sodium is not osmolality or tonicity

Corrected sodium estimates the glucose-related shift in measured sodium. It does not calculate total serum osmolality or effective osmolality/tonicity and should not be used as a substitute for those calculations.

Need calculated serum osmolality or an osmol gap? Open the Serum Osmolality Calculator →

Why glucose can make sodium look lower

Marked hyperglycaemia raises extracellular tonicity. Water then shifts from the intracellular space into the extracellular space, increasing extracellular water and diluting the measured sodium concentration.

This is why a patient can have a measured sodium that appears low while the glucose is very high, then show a rising measured sodium as glucose falls and water moves back into cells.

This mechanism is different from pseudohyponatraemia, which is a laboratory measurement artefact that can occur with indirect ion-selective electrode (ISE) methods in the presence of very high lipids or proteins. If that artefact is suspected, verify the sodium method or a direct ISE result; mathematically correcting the spuriously low sodium for glucose does not repair the measurement error.

Same patient, different correction factor

Corrected sodium comparison showing Katz 1.6 and Hillier 2.4 correction factors for hyperglycaemia.

The formula choice matters more as glucose rises. This is why MedMaths shows the selected method beside the result.

Input	Katz 1.6	Hillier 2.4	Difference
Na⁺ 128 mmol/L, glucose 27.8 mmol/L	134.4 mmol/L	137.6 mmol/L	3.2 mmol/L

Important: Hillier's experiment found 2.4 was a better overall correction factor than 1.6 across the study, but it also found a non-linear relationship at very high glucose. Do not interpret either factor as a biological constant that will be exact for every patient.

Worked examples

These examples teach the arithmetic and formula comparison only. They do not diagnose a sodium disorder or determine treatment.

Example 1 — Katz correction with severe hyperglycaemia

Measured sodium = 128 mmol/L, glucose = 500 mg/dL, Katz factor = 1.6.

Glucose above reference = 500 − 100 = 400 mg/dL.
Number of 100 mg/dL increments = 400 ÷ 100 = 4.
Sodium correction = 1.6 × 4 = 6.4 mmol/L.
Corrected sodium = 128 + 6.4 = 134.4 mmol/L.

Answer: 134.4 mmol/L using Katz.

Example 2 — Same patient using Hillier

Measured sodium = 128 mmol/L, glucose = 500 mg/dL, Hillier factor = 2.4.

Glucose above reference = 500 − 100 = 400 mg/dL.
Number of 100 mg/dL increments = 400 ÷ 100 = 4.
Sodium correction = 2.4 × 4 = 9.6 mmol/L.
Corrected sodium = 128 + 9.6 = 137.6 mmol/L.

Answer: 137.6 mmol/L using Hillier — 3.2 mmol/L higher than the Katz estimate for the same inputs.

Example 3 — Moderate hyperglycaemia in mmol/L

Measured sodium = 132 mmol/L, glucose = 16.7 mmol/L.

Convert glucose: 16.7 × 18 = 300.6 mg/dL.
Glucose above reference = 300.6 − 100 = 200.6 mg/dL.
Katz correction = 1.6 × (200.6 ÷ 100) = 3.21 mmol/L → corrected sodium 135.2 mmol/L.
Hillier correction = 2.4 × (200.6 ÷ 100) = 4.81 mmol/L → corrected sodium 136.8 mmol/L.

Answer: 135.2 mmol/L with Katz or 136.8 mmol/L with Hillier.

Example 4 — Very high glucose entered in mg/dL

Measured sodium = 126 mmol/L, glucose = 800 mg/dL, using Hillier.

Glucose above reference = 800 − 100 = 700 mg/dL.
700 ÷ 100 = 7 glucose increments.
Correction = 2.4 × 7 = 16.8 mmol/L.
Corrected sodium = 126 + 16.8 = 142.8 mmol/L.

Answer: 142.8 mmol/L using the calculator's Hillier pathway. At this glucose level, the fixed correction factor is only an estimate.

Quick corrected-sodium examples

The difference between Katz and Hillier expands as glucose rises because Hillier uses the larger correction factor.

Measured Na⁺	Glucose	Katz result	Hillier result
135 mmol/L	5.6 mmol/L	135.0 mmol/L	135.0 mmol/L
138 mmol/L	11.2 mmol/L	139.6 mmol/L	140.4 mmol/L
130 mmol/L	22.4 mmol/L	134.8 mmol/L	137.2 mmol/L
128 mmol/L	27.8 mmol/L	134.4 mmol/L	137.6 mmol/L
140 mmol/L	33.3 mmol/L	148.0 mmol/L	152.0 mmol/L

Why measured sodium may rise while glucose falls

As treatment lowers extracellular glucose, water shifts back into cells. The measured serum sodium can therefore rise even before considering sodium contained in IV fluids.

The 2024 adult hyperglycaemic-crisis consensus report describes an approximate 1.6 mmol/L rise in serum sodium for each 100 mg/dL (5.6 mmol/L) fall in glucose. This is one reason sodium trends should be interpreted together with glucose and osmolality rather than as an isolated number.

Common corrected-sodium mistakes

Using the wrong glucose unit

Entering 500 as mmol/L instead of 500 mg/dL creates a huge error. MedMaths now prompts for explicit unit verification when a value strongly resembles the alternate reporting scale.

Subtracting the correction

For hyperglycaemia the correction is added to measured sodium because the glucose-related water shift has lowered the measured concentration.

Calling it pseudohyponatraemia

Hyperglycaemia causes a real transcellular water shift. That mechanism is different from the laboratory artefact called pseudohyponatraemia.

Treating 1.6 or 2.4 as exact constants

Both factors are population-level estimates. Hillier's own results showed the sodium-glucose relationship was non-linear at very high glucose.

Mixing laboratory time points

Use sodium and glucose measured at the same time where possible, especially during active treatment when both can change quickly.

Ignoring osmolality

A low measured sodium in severe hyperglycaemia does not mean the plasma is hypotonic. Glucose itself raises tonicity.

Treating corrected sodium as a direct measurement

It is a calculated estimate. Serial measured sodium and the rest of the laboratory picture remain essential.

Using the result as a fluid prescription

Corrected sodium can support interpretation, but DKA/HHS fluid selection and rate require a full protocol and serial reassessment.

When corrected sodium is used

Corrected sodium is most often discussed when marked hyperglycaemia and an apparently low or normal measured sodium occur together. The calculation helps estimate how much of the measured sodium depression may be explained by glucose-related water movement.

In severe hyperglycaemia, the corrected estimate can also make a relative water deficit more visible. A patient can have a low measured sodium yet a normal or high corrected estimate because the hyperglycaemia is temporarily diluting the extracellular sodium concentration.

During DKA or HHS treatment, sodium, glucose and osmolality are dynamic. Use serial contemporaneous laboratory results and the relevant clinical protocol rather than relying on one corrected value in isolation.

Clinical limitations

•Corrected sodium is an estimate, not a directly measured laboratory value.
•Katz 1.6 and Hillier 2.4 are different population-level correction approaches and can diverge substantially in severe hyperglycaemia.
•Hillier's study involved six healthy subjects with experimentally induced acute hyperglycaemia. It found a non-linear sodium-glucose relationship at very high glucose concentrations, so a single fixed factor is not exact for every patient or every clinical setting.
•The calculation assumes glucose is mathematically normalised while body water, sodium and potassium are otherwise unchanged. Real DKA/HHS is an open system, so fluids, osmotic diuresis, insulin and electrolyte changes can alter subsequent measured sodium.
•The calculation does not replace measured serum osmolality, effective osmolality/tonicity assessment, or serial laboratory monitoring.
•Hyperglycaemia-related sodium lowering is not the same mechanism as pseudohyponatraemia from an indirect-ISE measurement artefact. If marked lipids/proteins or discordant osmolality raise that concern, verify the sodium measurement method/direct ISE rather than assuming glucose correction fixes it.
•The formula does not identify the cause of a sodium abnormality that remains after glucose correction.
•The result does not determine IV fluid composition, fluid rate, insulin therapy or electrolyte replacement by itself.
•Use sodium and glucose from the same clinical time point where possible because both can change rapidly during treatment.

Frequently Asked Questions

Want the interpretation rather than another calculation? Read Corrected sodium in hyperglycaemia explained →

Continue calculating

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Authorship and review

Clear authorship, review timing, and limits of use.

Formula authorMurray A. Katz, MDKatz hyperglycaemia sodium correction (1.6) formula · 1973

Written and reviewed byGeorge Lambroglou, RNReviewed 28 August 2026

Formula researchers listed above are credited for their published work only. They are not affiliated with, reviewed by, or endorsed by MedMaths. George Lambroglou, RN wrote and reviewed the MedMaths calculator content. Evidence reviewed against Katz 1973, Hillier et al. 1999, the 2020 corrected-sodium review, the 2023 pseudohyponatraemia review, the 2024 adult hyperglycaemic-crisis consensus, the 2024 RCPA equation comparison and ADA Standards of Care 2026. Corrected sodium is an interpretation aid, not a replacement measurement or stand-alone treatment rule.

References and sources

Open the original Katz and Hillier papers plus the current adult hyperglycaemic-crisis consensus source used for clinical context.

Katz 1.6 — original publication

Katz MA. Hyperglycemia-Induced Hyponatremia — Calculation of Expected Serum Sodium Depression. N Engl J Med. 1973;289(16):843–844. doi:10.1056/NEJM197310182891607.

PubMed PMID 4763428 Publisher / DOI record

Hillier 2.4 — experimental re-evaluation

Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999;106(4):399–403. doi:10.1016/S0002-9343(99)00055-8.

PubMed PMID 10225241 Publisher record

Hillier et al. reported 2.4 mmol/L per 100 mg/dL as the better overall estimate in their experiment and also found non-linearity at very high glucose concentrations.

2024 comparison of sodium-adjustment equations

Comparison of commonly used equations for sodium adjustment in hyperglycaemia. Pathology. 2024. Royal College of Pathologists of Australasia / Elsevier.

Full text

This comparison highlights that commonly used correction equations can diverge substantially in marked hyperglycaemia and that no single equation is a universal biological truth.

Current adult hyperglycaemic-crisis consensus

Umpierrez GE, et al. Hyperglycemic Crises in Adults With Diabetes: A Consensus Report. Diabetes Care. 2024;47(8):1257–1275. doi:10.2337/dci24-0032.

Consensus report / DOI PubMed PMID 39052901

The report describes an approximately 1.6 mmol/L rise in serum sodium for each 100 mg/dL (5.6 mmol/L) fall in glucose during HHS treatment and emphasises serial sodium, osmolality and clinical reassessment.

Corrected-sodium computation and clinical interpretation review

Tzamaloukas AH, et al. The Corrected Serum Sodium Concentration in Hyperglycemic Crises: Computation and Clinical Applications. Front Med. 2020;7:477.

PubMed Central full text

Describes the conventional corrected-sodium construct as normalising glucose to about 100 mg/dL while body water, sodium and potassium are otherwise unchanged, and explains why ongoing treatment can change the corrected value.

Pseudohyponatraemia and sodium measurement method

Ing TS, et al. Pseudohyponatremia: Mechanism, Diagnosis, Clinical Associations and Management. 2023.

PubMed Central full text

Inpatient hyperglycaemia guidance

American Diabetes Association Professional Practice Committee. Diabetes Care in the Hospital: Standards of Care in Diabetes—2026.

ADA Standards of Care 2026

Defines inpatient hyperglycaemia above 140 mg/dL; this is distinct from the corrected-sodium equation's 100 mg/dL arithmetic reference point.

Corrected Sodium Calculator

Lab corrections

What is the estimated corrected sodium?

Enter the measured sodium and blood glucose, then choose the glucose unit and correction formula.

Measured sodium (Na⁺)*mmol/L

Enter the measured serum sodium from the laboratory report.

Glucose unit

Choose the unit shown on the laboratory report.

Blood glucose*mmol/L

Enter the measured blood glucose in the selected unit.

Correction formula

Katz 1.6 is the classic correction. Hillier 2.4 is an alternative overall empirical estimate from a 1999 experimental study.

Katz uses a correction factor of 1.6 mmol/L per 100 mg/dL (5.55 mmol/L) rise above the equation's 100 mg/dL reference point. That reference is not a diagnostic hyperglycaemia threshold.

Use the laboratory values exactly as reported

Simple answer

How is sodium corrected for hyperglycaemia?

Start with the measured sodium, then add a glucose-dependent correction. MedMaths lets you choose either the Katz 1.6 factor or the Hillier 2.4 factor.

Example: Measured sodium 128 mmol/L with glucose 500 mg/dL (about 27.8 mmol/L) gives 134.4 mmol/L with Katz or 137.6 mmol/L with Hillier.

What does corrected sodium mean?

Katz 1.6 or Hillier 2.4?

Katz 1.6

The classic correction. The 2024 adult hyperglycaemic-crisis consensus still describes an approximately 1.6 mmol/L sodium rise for each 100 mg/dL fall in glucose during HHS treatment.

Hillier 2.4

An alternative overall empirical estimate from the 1999 Hillier study. The same study also found the relationship became non-linear at very high glucose.

Use corrected sodium as an interpretation aid

Clinical use and safety