Corrected Sodium

Corrects serum sodium for hyperglycemia using the conventional correction factor. Hyperglycemia draws water into the extracellular space, diluting sodium; this correction estimates what sodium would be at a normal glucose level.

Internal Medicine Internal MedicineEvidence-BasedUpdated 2026-08-06

Clinical decision-support tool for qualified healthcare professionals. Results are not a diagnosis and should not replace professional clinical judgment.

Clinical Notes

Severe hyperglycemia raises extracellular osmolality and draws water out of cells, diluting the extracellular sodium. The measured sodium therefore underestimates the body's true sodium status in a hyperglycemic patient. This calculator applies a conventional correction factor (adding approximately 1.6 mmol/L of sodium for every 100 mg/dL of glucose above 100 mg/dL) to estimate the sodium level expected at a euglycemic glucose concentration. The corrected value is an estimate used to put the measured sodium into clinical context; it is not a separate laboratory measurement and does not replace the measured sodium for every purpose. Recording and trending both the corrected and the measured sodium helps distinguish true hyponatremia from the spurious, dilutional fall caused by hyperglycemia, and anticipates how sodium will change as glucose falls during treatment. The correction factor is an approximation. Its accuracy varies with the glucose range and clinical circumstances; at very high glucose concentrations the linear factor becomes less reliable, and some references propose a larger correction factor in that range. Unmeasured osmotic solutes, such as mannitol, produce hypertonicity without hyperglycemia and are not captured by this formula. Interpret the result together with volume status, other electrolytes, renal function, and osmolality. This is a decision-support estimate for clinical interpretation; it does not by itself establish a diagnosis or dictate a treatment plan.

Calculator Information

Specialty

Internal Medicine

📋 Reference Ranges

Normal Range

135–145 mmol/L

Reference ranges for this calculator
Classification	Range
Hyponatremia (corrected)	<134.1
Normal corrected sodium	135–145
Hypernatremia (corrected)	≥146
Severe hypernatremia	≥160

What This Calculator Measures

Corrects the measured serum sodium for hyperglycemia to reveal the true sodium status in patients with significant glucose elevation.

How to Use

Enter the measured serum sodium in mmol/L.
Enter the serum glucose in mg/dL.
Review the corrected sodium value.

How the Calculation Works

Corrected sodium = measured sodium + 1.6 x ((glucose - 100) / 100) when glucose exceeds 100 mg/dL, adjusting for hyperglycemia-induced dilutional hyponatremia.

Variables Explained

Measured Sodium

Measured serum sodium in mmol/L, to which the glucose correction is added.

Glucose

Serum glucose in mg/dL; the amount above 100 mg/dL drives the correction.

Interpretation Guide

Corrected sodium accounts for the dilutional effect of glucose. For every 100 mg/dL increase in glucose above 100 mg/dL, sodium decreases by approximately 1.6 mmol/L. A normal corrected sodium with a low measured sodium indicates true dilutional hyponatremia.

Clinical Significance

In hyperglycemic states, water shifts from the intracellular to the extracellular space, diluting serum sodium. Without correction, the true sodium status may be masked, leading to inappropriate fluid management.

When It Is Useful

Diabetic ketoacidosis (DKA)
Hyperosmolar hyperglycemic state (HHS)
Any condition with significant hyperglycemia
Interpretation of sodium in uncontrolled diabetes

When It Is Not Useful

When glucose is normal or only mildly elevated
As a replacement for clinical assessment of fluid status

Common Mistakes

Applying the correction when glucose is normal or only mildly elevated, where it adds little beyond noise to the interpretation.
Expecting the formula to capture hypertonicity from osmotic agents such as mannitol or glycine, which it does not include.
Trusting the 1.6 mmol/L per 100 mg/dL factor at glucose levels above 600 mg/dL, where it becomes less reliable.

Limitations

The correction factor (1.6 mmol/L per 100 mg/dL glucose) is an approximation.
May be less accurate at very high glucose levels (>600 mg/dL).
Does not account for other osmotic agents (mannitol, glycine).
Should be used alongside clinical assessment of volume status.

Worked Example

A 58-year-old woman with DKA has a measured sodium of 128 mmol/L and glucose of 500 mg/dL.

Inputs:

sodium: 128

glucose: 500

Expected Result: Corrected sodium ≈ 128 + 1.6 × (500−100)/100 = 128 + 6.4 = 134.4 mmol/L. The corrected value remains mildly low, showing that glucose-driven dilution accounts for a large part (6.4 mmol/L) of the measured fall.

Evidence & References

Source:: Endocrinology / Nephrology
Content updated:: 2026-08

Hillier TA, Abbott RD, Barrett EJ. Am J Med. 1999;106:399-403.

References

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

Frequently Asked Questions

Why does hyperglycemia lower sodium?

High glucose increases serum osmolality, drawing water from the intracellular to the extracellular space. This dilutes the serum sodium, causing a falsely low measured value. The corrected sodium estimates what the sodium would be at a normal glucose.

What correction factor should I use?

The conventional correction factor is 1.6 mmol/L for every 100 mg/dL increase in glucose above 100 mg/dL. For very high glucose (> 400 mg/dL), some experts use a factor of 2.0–2.4.

When should I correct sodium for glucose?

Correct sodium whenever glucose is significantly elevated (> 200 mg/dL), especially in diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS), to accurately assess the patient's true sodium status.

Disclaimer: This calculator is intended for educational and clinical decision support purposes only. Sodium correction is an approximation and should be interpreted alongside clinical assessment of the patient's volume and glucose status.