Corrected sodium = measured Na + 1.6 × (glucose − 100) / 100, with glucose in mg/dL. It estimates the serum sodium once hyperglycemia resolves. For Na 130 mEq/L and glucose 600 mg/dL, corrected sodium is 138 mEq/L using the Katz factor, or 142 mEq/L using the Hillier factor of 2.4.
This page is for clinicians and students managing hyperglycemic patients. Glucose can be entered in mg/dL or mmol/L, and both correction factors are shown so you can see how much the choice matters at your patient's glucose.
How to use this calculator
- Enter the measured serum sodium in mEq/L (numerically the same as mmol/L).
- Enter the serum glucose and pick mg/dL or mmol/L.
- Read the corrected sodium with the Katz factor (1.6) and the Hillier factor (2.4).
- Above 400 mg/dL a note appears, because that is where the two factors diverge most.
- Repeat as glucose falls. The corrected value should stay fairly steady; a rising corrected sodium means water is being lost.
How corrected sodium is calculated
Corrected Na = measured Na + factor × (glucose − 100) / 100
- Measured Na is the laboratory serum sodium.
- Glucose is in mg/dL. For mmol/L, the calculator multiplies by 18.016, so 30 mmol/L becomes 540.5 mg/dL.
- 100 is taken as a normal glucose; no correction is applied at 100 mg/dL.
- Factor is 1.6 (Katz, 1973), the value quoted in StatPearls, or 2.4 (Hillier et al., 1999).
Below 100 mg/dL the formula gives a small negative adjustment, which is rarely clinically meaningful.
Katz 1.6 vs Hillier 2.4
Katz derived 1.6 mEq/L per 100 mg/dL theoretically in 1973. Hillier and colleagues tested it experimentally in 1999: they gave somatostatin to block insulin in 6 healthy volunteers, raised glucose above 600 mg/dL within an hour with 20% dextrose, and measured sodium every 10 minutes. The average fall was 2.4 mEq/L per 100 mg/dL, and the relationship was not linear. Up to 400 mg/dL the standard 1.6 worked well; above 400 mg/dL a factor of 4.0 fit better.
Ing et al. (2020) reviewed the theory and clinical reports and concluded that 1.6 is a reasonable estimate in most clinical settings, except extreme hyperglycemia or profound hypervolemia. Many guidelines still use 1.6. Showing both lets you see how wide the plausible range is:
| Glucose (mg/dL) | Add (Katz 1.6) | Add (Hillier 2.4) | Corrected, Na 135 (1.6) | Corrected, Na 135 (2.4) |
|---|---|---|---|---|
| 100 | +0.0 | +0.0 | 135.0 | 135.0 |
| 200 | +1.6 | +2.4 | 136.6 | 137.4 |
| 300 | +3.2 | +4.8 | 138.2 | 139.8 |
| 400 | +4.8 | +7.2 | 139.8 | 142.2 |
| 500 | +6.4 | +9.6 | 141.4 | 144.6 |
| 600 | +8.0 | +12.0 | 143.0 | 147.0 |
| 800 | +11.2 | +16.8 | 146.2 | 151.8 |
| 1000 | +14.4 | +21.6 | 149.4 | 156.6 |
Worked examples
These figures are generated by the calculator's own code. Tonicity is shown using StatPearls' formula, 2 × Na + glucose / 18.
- Na 130, glucose 600 mg/dL. Corrected sodium is 138.0 mEq/L (1.6) or 142.0 mEq/L (2.4). Tonicity is about 293 mOsm/kg, against a reference range of 285–295.
- Na 125, glucose 400 mg/dL. Corrected sodium is 129.8 mEq/L (1.6) or 132.2 mEq/L (2.4). Tonicity is about 272 mOsm/kg, against a reference range of 285–295.
- Na 128, glucose 1000 mg/dL. Corrected sodium is 142.4 mEq/L (1.6) or 149.6 mEq/L (2.4). Tonicity is about 312 mOsm/kg, against a reference range of 285–295.
- Na 132, glucose 30 mmol/L. That is 540.5 mg/dL, giving a corrected sodium of 139.0 mEq/L (1.6) or 142.6 mEq/L (2.4).
The last example in mg/dL shows why the factor matters: at glucose 1,000 mg/dL a measured sodium of 128 corrects to a normal value with 1.6 but to a hypernatremic value with 2.4.
Why hyperglycemia lowers the measured sodium
StatPearls classifies hyponatremia by tonicity, calculated as 2 × Na + glucose / 18 with a reference range of 285–295 mOsm/kg. Hyperglycemia is a cause of hypertonic hyponatremia (above 295 mOsm/kg): glucose pulls water out of cells, diluting the sodium even though the blood is concentrated. Mannitol and some other exogenous solutes do the same.
That is different from pseudohyponatremia, which StatPearls calls a laboratory artifact. It is usually caused by severe hypertriglyceridemia, lipoprotein X or hyperproteinemia (for example monoclonal gammopathy or IV immunoglobulin), and the osmolality is normal (275–295 mOsm/kg). The glucose correction does not apply to it.
Corrected sodium in DKA and HHS
StatPearls notes that the measured sodium is often falsely low in diabetic ketoacidosis, and that the choice of maintenance fluid depends partly on sodium: 0.45% saline for a high sodium, 0.9% saline for a low sodium, alongside hemodynamics and urine output.
The 2024 consensus report from the ADA, EASD, JBDS, AACE and DTS adds points that bear directly on the corrected value:
- As glucose falls, sodium can rise by 1.6 mmol/L for each 100 mg/dL (5.6 mmol/L) drop. That initial rise alone is not an indication for hypotonic fluids.
- In HHS, sodium should fall by no more than 10 mmol/L in 24 hours, and osmolality by no more than 3.0–8.0 mOsm/kg per hour.
- About 10% of DKA presents with glucose below 200 mg/dL (euglycemic DKA), where the correction is small and the measured sodium is closer to the truth.
Ing et al. (2020) found the average corrected sodium was in the normal range in DKA (141.1 mmol/L over 7,812 cases) but in the severe hypernatremic range in HHS (160.8 mmol/L over 755 cases), reflecting larger water losses from osmotic diuresis. They also note the corrected value can change during treatment because of ongoing losses, so recalculate as you go.
DKA workups usually include an anion gap and a check on respiratory compensation; see the anion gap calculator and Winter's formula calculator. For longer-term glucose control, the A1C calculator converts A1C to estimated average glucose.
Common mistakes
- Mixing units. Entering a mmol/L glucose as mg/dL understates the correction about eighteen-fold.
- Correcting pseudohyponatremia. If osmolality is normal and lipids or proteins are very high, the problem is the assay, not water shift.
- Treating one factor as exact. At glucose above 400 mg/dL the true correction may be larger than 1.6 predicts.
- Reacting to the measured rise. A measured sodium that climbs while glucose falls is expected; watch the corrected value and the osmolality instead.
For healthcare professionals and students only. The corrected value is an estimate, this tool gives no medical advice, and it does not replace clinical judgement, your laboratory's reference ranges or local DKA/HHS protocols. Fluid and electrolyte decisions must be made by the treating team. Patients with questions about their own sodium level should speak to their care team.
Frequently asked questions
What is the corrected sodium formula?
Corrected Na = measured Na + 1.6 × (glucose − 100) / 100, with glucose in mg/dL (Katz, 1973). StatPearls describes it as adding 1.6 mEq/L for each 100 mg/dL of glucose above 100.
Should I use 1.6 or 2.4?
Both are in use. Hillier et al. (1999) measured an average of 2.4 mEq/L per 100 mg/dL; they found 1.6 held up to about 400 mg/dL and a factor of 4.0 fit better above that. This calculator shows the 1.6 and 2.4 results side by side.
What is the corrected sodium for Na 130 and glucose 600?
138 mEq/L with the 1.6 factor, or 142 mEq/L with 2.4.
What is the corrected sodium for Na 125 and glucose 400?
129.8 mEq/L with the 1.6 factor, or 132.2 mEq/L with 2.4.
Why does high glucose lower sodium?
Glucose acts as an extracellular solute, so a high level draws water out of cells into the blood and dilutes the measured sodium. The corrected value estimates what the sodium would be once the glucose is back to normal.
How do I correct sodium when glucose is in mmol/L?
Convert glucose to mg/dL first by multiplying by about 18 (this calculator uses 18.016), or switch the unit selector to mmol/L. The ADA consensus report pairs 100 mg/dL with 5.6 mmol/L, so the Katz rule is also 1.6 mmol/L of sodium per 5.6 mmol/L of glucose.
Is corrected sodium the same as pseudohyponatremia?
No. Hyperglycemia causes a true dilutional (hypertonic) hyponatremia. StatPearls describes pseudohyponatremia as a laboratory artifact, usually from very high triglycerides, lipoprotein X or very high protein levels, with a normal serum osmolality.
Will the sodium rise during DKA treatment?
It can. The 2024 ADA-led consensus report notes that each 100 mg/dL fall in glucose can raise sodium by 1.6 mmol/L as water moves back into cells, and that this initial rise alone is not an indication for hypotonic fluids.
What does a high corrected sodium mean in hyperglycemia?
A corrected value above the normal range suggests water has been lost in excess of sodium, typically through osmotic diuresis. Ing et al. (2020) found mean corrected sodium was 141.1 mmol/L across 7,812 DKA cases but 160.8 mmol/L across 755 HHS cases.
What is a normal serum sodium?
StatPearls defines hyponatremia as a serum sodium below 135 mEq/L, graded mild (130–135), moderate (125–130) or severe (below 125). Thresholds vary slightly between laboratories.
Sources & method
- StatPearls (NCBI Bookshelf) — Adult diabetic ketoacidosis (sodium correction 1.6 per 100 mg/dL)
- StatPearls (NCBI Bookshelf) — Hyponatremia (tonicity, pseudohyponatremia, severity bands)
- Katz (1973), N Engl J Med — hyperglycemia-induced hyponatremia
- Hillier et al. (1999), Am J Med — hyponatremia: evaluating the correction factor for hyperglycemia
- Ing et al. (2020), Front Med — the corrected serum sodium concentration in hyperglycemic crises
- Umpierrez et al. (2024), Diabetes Care — Hyperglycemic crises in adults with diabetes: a consensus report (ADA/EASD/JBDS/AACE/DTS)
Results are estimates for general information. Found an error? It helps everyone — see our methodology.