Corrected Sodium Calculator

What is Corrected Sodium?

Corrected sodium (also referred to as sodium corrected for glucose) is a clinical calculation used to estimate a patient's true sodium level in the presence of high blood sugar (hyperglycemia). It helps differentiate true hyponatremia from pseudohyponatremia caused by glucose-induced fluid shifts. For related clinical tools, try the Corrected Calcium Calculator and GFR Calculator.

Why Does Hyperglycemia Lower Sodium?

Glucose is an active solute that does not freely cross cell membranes. When blood glucose levels rise, it increases extracellular osmolality. This acts as an osmotic force, drawing water out of the cells and into the bloodstream. This extra water dilutes the sodium concentration in the blood, causing measured sodium levels to appear lower than they actually are.

The Corrected Sodium Formula

The standard formula to correct sodium for glucose levels above 100 mg/dL is:

$$\text{Corrected Sodium} = \text{Measured Sodium} + F \times \left( \frac{\text{Glucose} - 100}{100} \right)$$

Where $F$ is the correction factor:

• 1.6 is the standard Hillier factor, widely used for moderate hyperglycemia.
• 2.4 is often used for severe hyperglycemia (glucose > 400 mg/dL), as described by Katz.