Sodium Correction for Hyperglycemia

Introduction
A relative dilutional hyponatremia can occur in the presence of serum hyperglycemia. Hyperglycemia causes osmotic shifts from the intracellular to the extracellular spaces in the body. The original correction factor of 1.6 mEq/L for every 100 mg/dL increase in serum glucose was established by Katz (1973). Hillier et al (1999) challenged the original factor and proposes a factor of 2.4 mEq/L as a more accurate alternative. 

Formula
There are two proposed ways of evaluating the correction factor for hyperglycemia-induced hyponatremia.

Corrected Sodium (Katz, 1973) = Measured sodium + 0.016 * (Serum glucose - 100)

Corrected Sodium (Hillier, 1999) = Measured sodium + 0.024 * (Serum glucose - 100)

Note: Serum glucose must be in mg/dL

Katz MA. Hyperglycemia-induced hyponatremia--calculation of expected serum sodium depression. N Engl J Med. 1973 Oct 18;289(16):843-4. doi: 10.1056/NEJM197310182891607. PMID: 4763428.

Hillier TA, Abbott RD, Barrett EJ. Hyponatremia: evaluating the correction factor for hyperglycemia. Am J Med. 1999 Apr;106(4):399-403. doi: 10.1016/s0002-9343(99)00055-8. PMID: 10225241.