What is corrected sodium in hyperglycemia?
High blood glucose draws water osmotically into the vascular space, diluting serum sodium without reflecting a true change in total body sodium or water balance - a phenomenon called pseudohyponatremia or translocational hyponatremia. This matters most in diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS), where glucose is often markedly elevated and the measured sodium can look falsely low.
How to calculate corrected sodium
Two correction formulas are in common use:
- Katz (1973): Corrected Na = Measured Na + 1.6 x [(Glucose - 100) / 100]
- Hillier (1999): Corrected Na = Measured Na + 2.4 x [(Glucose - 100) / 100]
Both use glucose in mg/dL. Katz is the traditional, more commonly taught formula. Hillier's study suggested the correction factor is larger than originally thought, especially at very high glucose levels (e.g. above 400 mg/dL), which is why this calculator shows both.
Interpretation
Once corrected, interpret the result like any other sodium value: roughly 135-145 mEq/L is normal. If the corrected sodium is still low, that supports a true hyponatremia requiring its own workup rather than one fully explained by hyperglycemia alone.
References
Katz MA. Hyperglycemia-induced hyponatremia - calculation of expected serum sodium depression. N Engl J Med. 1973. Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999.
See also: Electrolyte Disorders Guide — sodium, potassium, and calcium.