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Corrected Sodium in Hyperglycemia

In hyperglycaemia, serum sodium falls as water shifts out of cells. Corrected Na = Na + 1.6 × (glucose − 100)/100 mg/dL (Katz) or + 2.4 per 100 mg/dL (Hillier, more accurate at very high glucose). In SI, add 1.6 or 2.4 per 5.6 mmol/L of glucose above 5.6.

  • Serum sodium (mmol/L or mEq/L)
  • Serum glucose (mg/dL or mmol/L)
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Interpretation

ResultMeaning
< 135True hyponatraemia
135–145Normal
> 145Hypernatraemia (water deficit)

Formula

Katz: Na + 1.6 × (glucose mg/dL − 100) ÷ 100. Hillier: Na + 2.4 × (glucose − 100) ÷ 100. SI: glucose mg/dL = mmol/L × 18. No correction applied when glucose ≤100 mg/dL (5.6 mmol/L).

Clinical pearls

  • Hillier found 2.4 per 100 mg/dL fits better overall, especially above 400 mg/dL (22 mmol/L); the Katz 1.6 factor is the traditional one.
  • A rising corrected sodium during DKA/HHS treatment is expected as glucose falls; a falling corrected sodium raises concern for cerebral oedema.

Examples

corrected sodium na 130 glucose 600corrected na 128 glucose 45 mmol/Ldka sodium 132 sugar 32 mmol

FAQ

Should I use 1.6 or 2.4 to correct sodium for glucose?

Both are used; 2.4 (Hillier) is more accurate overall and at glucose above 400 mg/dL, while 1.6 (Katz) is the traditional factor in many DKA protocols.

Is hyperglycaemic hyponatraemia pseudohyponatraemia?

No. It is a real (translocational) hyponatraemia from water shifting out of cells, unlike lab-artifact pseudohyponatraemia from high lipids or protein.

Evidence

  1. Katz MA. Hyperglycemia-induced hyponatremia — calculation of expected serum sodium depression. N Engl J Med 1973;289:843–4.
  2. Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med 1999;106:399–403.

Nephrology & Electrolytes · Reviewed 2026-10-14 · Methodology