Corrected Sodium for Glucose Calculator

About this calculator

Measured serum sodium falls artificially low when blood glucose is high, because the osmotic pull of extra glucose draws water out of cells and dilutes the sodium concentration in the blood — a state called translational hyponatremia rather than true sodium loss. The Katz correction (adding 1.6 mmol/L of sodium for every 100 mg/dL of glucose above 100 mg/dL) is the classic bedside formula, while the Hillier correction uses a steeper factor of 2.4 mmol/L per 100 mg/dL, derived from more recent clinical data showing the Katz formula underestimates the effect at very high glucose levels.

Clinicians use this correction when managing diabetic ketoacidosis, hyperosmolar hyperglycemic state, or any patient presenting with both hyperglycemia and low measured sodium, because treating the raw sodium number without correcting for glucose can lead to overly aggressive or unnecessary sodium replacement. The corrected value tells the treating team whether a patient's sodium is truly low, truly normal, or only appears low because of the glucose effect.

This calculator takes your measured sodium and glucose values and returns the corrected sodium under both the Katz and Hillier methods side by side, so you can see how the choice of formula affects the clinical picture.