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Sodium Correction for Hyperglycemia — Free Online Calculator

Input

mEq/L
mg/dL

Corrected Na⁺ (Katz)

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Corrected Na⁺ (Hillier)

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About This Calculator

In hyperglycemia, water shifts from intracellular to extracellular space due to the osmotic effect of glucose, diluting serum sodium. The corrected sodium estimates what the sodium level would be if glucose were normal. This is important for assessing true sodium status in patients with diabetic ketoacidosis (DKA) or hyperosmolar hyperglycemic state (HHS).

Formula

Katz (1973): Corrected Na = Measured Na + 1.6 × [(Glucose − 100) / 100]
Hillier (1999): Corrected Na = Measured Na + 2.4 × [(Glucose − 100) / 100]
Glucose in mg/dL. The Hillier formula may be more accurate at very high glucose levels.

Interpretation

Corrected Na (mEq/L)Interpretation
< 135Hyponatremia
135 – 145Normal
> 145Hypernatremia

References

  1. Katz MA. Hyperglycemia-induced hyponatremia — calculation of expected serum sodium depression. N Engl J Med. 1973;289(16):843-844.
  2. Hillier TA, et al. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999;106(4):399-403.

Frequently Asked Questions

Why does hyperglycemia cause hyponatremia?

Elevated blood glucose creates an osmotic gradient that draws water from the intracellular space into the extracellular space, diluting serum sodium. This is dilutional hyponatremia — sodium is not truly depleted, it is redistributed. Correcting glucose often normalizes sodium.

What correction factor is used for sodium?

The traditional Katz formula adds 1.6 mEq/L to measured sodium for every 100 mg/dL increase in glucose above 100 mg/dL. The Hillier formula uses a correction factor of 2.4 mEq/L per 100 mg/dL when glucose exceeds 400 mg/dL, reflecting a non-linear relationship.

When is sodium correction for hyperglycemia clinically important?

This correction is critical in diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS). A corrected sodium that is normal or elevated indicates significant free water deficit. It also helps predict whether sodium will rise to dangerous levels as glucose is treated.

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⚠ Medical Disclaimer

This tool is for educational and informational purposes only. It is not intended to replace professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional for clinical decisions.