Sodium Correction for Hyperglycemia Calculator — Katz & Hillier Formulas
Calculate corrected serum sodium in severe hyperglycemia (DKA / HHS) to prevent misdiagnosis of true hyponatremia and guide fluid therapy.
Sodium Correction Calculator
Enter values below to calculate
Serum sodium from BMP.
Blood glucose level.
This calculator is for informational and educational purposes. Results should be interpreted with clinical judgment and local guidelines.
What is Corrected Sodium for Hyperglycemia?
Corrected Sodium is the calculated serum sodium concentration adjusted for the osmotic translocation of water caused by severe hyperglycemia. Glucose is an osmotically active solute that stays in the extracellular fluid (ECF) space in insulin-deficient states (such as Diabetic Ketoacidosis [DKA] or Hyperosmolar Hyperglycemic State [HHS]). High ECF glucose draws water out of cells into the intravascular space, diluting serum sodium concentrations—a phenomenon known as hyperosmolar pseudohyponatremia. The standard Katz formula adds 1.6 mEq/L to measured sodium for every 100 mg/dL of glucose above 100 mg/dL, while the Hillier formula uses 2.4 mEq/L for glucose levels > 400 mg/dL.
Corrected Na (Katz) = Measured Na + 0.016 × (Glucose mg/dL − 100). Corrected Na (Hillier) = Measured Na + 0.024 × (Glucose mg/dL − 100). Normal serum sodium: 135–145 mEq/L.
When to Use the Sodium Correction Calculator
- Initial evaluation and management of Diabetic Ketoacidosis (DKA) and Hyperosmolar Hyperglycemic State (HHS) in the emergency department or ICU.
- Selecting appropriate IV fluid replacement therapy: ADA DKA guidelines recommend switching from 0.9% Normal Saline to 0.45% Half-Normal Saline once corrected sodium is normal or high.
- Evaluating hyperosmolar states in patients with severe uncontrolled diabetes, parenteral nutrition, or high-dose corticosteroid therapy.
- Preventing rapid, iatrogenic shifts in serum osmolality and cerebral edema during fluid resuscitation in pediatric and adult DKA.
Sodium Correction Formulas
Katz Formula (Standard 1.6 factor)
Corrected Na = Measured Na + 1.6 × [(Glucose mg/dL − 100) / 100]
Na = 130 mEq/L, Glucose = 600 mg/dL → Corrected Na = 130 + 1.6 × 5 = 138 mEq/L (Normal!)
Hillier Formula (2.4 factor for glucose > 400 mg/dL)
Corrected Na = Measured Na + 2.4 × [(Glucose mg/dL − 100) / 100]
Na = 130 mEq/L, Glucose = 600 mg/dL → Corrected Na = 130 + 2.4 × 5 = 142 mEq/L
Variables
Measured Sodium (mEq/L (or mmol/L))
Measured serum sodium from basic metabolic panel.
Serum Glucose (mg/dL (or mmol/L))
Measured blood glucose level. 1 mmol/L = 18 mg/dL.
Katz (1.6) is standard for glucose < 400 mg/dL; Hillier (2.4) is validated for severe hyperglycemia (> 400 mg/dL).
Clinical Interpretation & IV Fluid Selection
Calculated corrected sodium guides IV fluid choice during DKA/HHS resuscitation according to American Diabetes Association (ADA) protocols.
| Range | Classification | Health Risk |
|---|---|---|
| < 135 mEq/L | True Hyponatremia | Continue 0.9% NaCl infusion at 250–500 mL/hr. |
| 135–145 mEq/L | Normal Corrected Sodium | Switch IV fluids to 0.45% NaCl (Half-Normal Saline) at 250–500 mL/hr. |
| > 145 mEq/L | Corrected Hypernatremia | Significant intracellular dehydration. Use 0.45% NaCl. Monitor osmolality closely. |
Check serum potassium before starting insulin! Insulin drives sodium and potassium into cells. Do NOT start insulin if K⁺ < 3.3 mEq/L.
Limitations & Clinical Warnings
Only applies to hyperglycemia-induced pseudohyponatremia.
Does not correct for pseudohyponatremia caused by severe hypertriglyceridemia or hyperproteinemia (multiple myeloma).
Fluid correction rate should not exceed 10–12 mEq/L per 24 hours to avoid osmotic demyelination syndrome (ODS).
Medical Disclaimer
Calculated corrected sodium is an aid for DKA/HHS fluid protocols. Follow institutional endocrinology guidelines.
References & Citations
- Katz MA. “Hyperglycemia-induced hyponatremia—calculation of expected serum sodium depression”. New England Journal of Medicine. 1973. 289(16): 843–844. PMID: 4740441
- Hillier TA, Abbott RD, Barrett EJ. “Hyponatremia: evaluating the correction factor for hyperglycemia”. American Journal of Medicine. 1999. 106(4): 399–403. PMID: 10225241
Medically Reviewed
Reviewed by CliniqWise Clinical Advisory Board — Endocrinology & Critical Care Panel · Last updated: 2026-08-27 · Next review: 2027-02-27
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