Sodium Correction Calculator
Calculate corrected serum sodium for hyperglycemia using the Hillier and Katz formulas. Free online medical tool for accurate sodium adjustment accounting for blood glucose levels.
About This Calculator
Our Sodium Correction Calculator adjusts measured serum sodium (Na⁺) levels for the dilutional effect of hyperglycemia. When blood glucose is elevated, water shifts from inside cells to the bloodstream, artificially lowering measured sodium concentration. This free medical calculator uses two validated formulas to estimate the true corrected sodium level, helping healthcare professionals and students make accurate electrolyte assessments in patients with diabetes, diabetic ketoacidosis (DKA), and hyperosmolar hyperglycemic state (HHS).
The calculator applies the Hillier formula (1998), the current clinical standard: Corrected Na⁺ = Measured Na⁺ + 0.024 × (Serum Glucose − 100), with glucose in mg/dL. It also displays the older Katz formula (1973) using a 0.016 correction factor for comparison. Both formulas assume a normal glucose level of 100 mg/dL (5.55 mmol/L) as the reference point. The corrected sodium better reflects the patient's true sodium balance and guides appropriate fluid and electrolyte management.
Regional Notes
India: Glucose is typically reported in mg/dL (multiply mmol/L by 18.0182 to convert). Serum sodium normal range: 135–145 mEq/L. Common in ICUs and emergency departments managing DKA and HHS.
United States: Glucose is reported in mg/dL. Sodium correction is standard practice in emergency medicine, critical care, and endocrinology. Both Hillier and Katz formulas are taught in medical education.
United Kingdom: Glucose may be reported in both mmol/L and mg/dL. The Hillier formula is preferred in clinical guidelines. Sodium unit mEq/L is equivalent to mmol/L for monovalent ions.
Frequently Asked Questions
What is the formula for corrected sodium in hyperglycemia?
The Hillier formula (1998) is: Corrected Na = Measured Na + 0.024 × (Serum Glucose − 100), with glucose in mg/dL. The older Katz formula (1973) uses 0.016 as the correction factor instead of 0.024.
Why does hyperglycemia lower measured sodium levels?
Hyperglycemia causes water to shift from the intracellular space to the extracellular space to dilute excess glucose. This dilution effect artificially lowers measured serum sodium concentration, requiring a correction formula to estimate the true sodium level.
What is the normal range for corrected sodium?
The normal serum sodium range is 135–145 mEq/L regardless of correction status. A corrected sodium below 135 indicates hyponatremia and above 145 indicates hypernatremia. Both formulas (Hillier and Katz) estimate what the sodium would be if glucose were normal (100 mg/dL).
Which corrected sodium formula is more accurate: Hillier or Katz?
The Hillier formula (1998) with a correction factor of 0.024 is more accurate and is the current clinical standard. The Katz formula (1973) with 0.016 was the original equation but tends to underestimate the correction needed for significant hyperglycemia.
When should corrected sodium be used clinically?
Corrected sodium should be used when managing patients with significant hyperglycemia (blood glucose > 200 mg/dL or 11.1 mmol/L) to assess true hyponatremia or hypernatremia before initiating treatment. It is especially important in diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS).
How does corrected sodium differ from measured sodium in DKA?
In diabetic ketoacidosis (DKA), measured sodium is often falsely low due to hyperglycemia-induced water shifts. Corrected sodium typically reveals a normal or even elevated true sodium level. As DKA resolves and glucose falls, the measured sodium rises toward the corrected value, a phenomenon known as pseudohyponatremia of hyperglycemia.
Can I rely on this for diagnosis?
This calculator is for educational and reference purposes only. It uses standard medical formulas but should not replace professional clinical judgment. Always consult a healthcare provider for diagnosis and treatment decisions based on corrected sodium values.
What is pseudohyponatremia and how does it relate to sodium correction?
Pseudohyponatremia is a falsely low measured sodium level caused by hyperglycemia, hyperlipidemia, or hyperproteinemia. The sodium correction formula specifically addresses the glucose-related pseudohyponatremia by adjusting for the osmotic effect of elevated blood glucose on water distribution between intracellular and extracellular compartments.