Corrected Sodium Calculator

This calculator estimates serum sodium corrected for hyperglycemia using two published factors: 1.6 and 2.4 mEq/L added per 100 mg/dL glucose above 100 mg/dL. High extracellular glucose draws water outward from cells and can lower measured sodium concentration.

Corrected sodium is a clinical estimate, not a replacement for measured electrolytes, tonicity assessment, volume status, or urgent treatment. Severe hyperglycemia and sodium abnormalities can be emergencies. A qualified clinician must interpret the laboratories and manage correction safely.

1. Enter measured serum sodium and select mmol/L or mEq/L; these are numerically equivalent for sodium.
2. Enter glucose and select mg/dL or mmol/L.
3. Select Calculate. mmol/L glucose is multiplied by 18 to obtain mg/dL.
4. If glucose exceeds 100 mg/dL, the page shows Katz-style 1.6 and Hillier 2.4 estimates. At or below 100, it leaves sodium unchanged.

Use values from the same blood sample and verify units against the laboratory report.

The estimate helps distinguish a glucose-related dilutional effect from sodium disturbance that persists after adjustment. It does not directly state total body sodium, free-water deficit, effective osmolality, or a safe fluid plan.

Hillier’s small experimental study found nonlinearity, especially above 400 mg/dL, and reported that 2.4 was a better overall estimate than 1.6. Reviews note ongoing variation by setting and physiology. Renal function, osmotic diuresis, treatment, and fluid balance matter. Clinicians should follow current protocols and serial laboratories rather than making treatment changes from one online result.

Glucose conversion here uses 18 mg/dL for each mmol/L. Laboratory conversion factors may be presented with more precision, so a result can differ slightly after rounding. Keep the original report and selected units visible when communicating the estimate.

The calculation models a translocational water shift and should not be confused with laboratory pseudohyponatremia caused by some measurement methods in marked hyperlipidemia or hyperproteinemia. These mechanisms require different evaluation. Corrected sodium also does not replace calculated effective osmolality or direct osmolality measurement when clinically indicated.

During treatment of diabetic ketoacidosis or hyperosmolar states, glucose, sodium, potassium, water balance, and osmolality change together. A sequence of measurements and clinical observations is more informative than a single corrected value. Rapid or inappropriate changes can be dangerous, which is why treatment belongs under a clinical protocol.

The result is rounded to two decimal places, but that display precision should not be mistaken for physiologic accuracy. Uncertainty in the factor is much larger than the final decimal digits.