Corrected Sodium for Glucose Calculator

About this calculator

High blood glucose pulls water osmotically out of cells and into the bloodstream, which dilutes serum sodium and can make a patient's measured sodium look falsely low even when their total body sodium is normal — a phenomenon called translocational or dilutional hyponatremia. The Katz formula corrects for this: corrected Na = measured Na + 1.6 × ((glucose − 100) / 100), adding back roughly 1.6 mEq/L of sodium for every 100 mg/dL of glucose above normal.

Without this correction, a hyperglycemic patient's true sodium status can be misjudged, leading to unnecessary workup for hyponatremia or, conversely, missing a real sodium disturbance that's masked by the glucose effect. Emergency physicians, internists, and endocrinologists use the Katz correction when interpreting labs in patients with significant hyperglycemia, such as those presenting with diabetic ketoacidosis or hyperosmolar hyperglycemic state.