Acid-Base & ElectrolytesEvidence-Based Golden Standard
Corrected Sodium for Hyperglycemia (Katz & Hillier Formulas)
Estimates true intravascular sodium concentration by correcting for the osmotic shift of water from the intracellular to extracellular fluid in marked hyperglycemia (DKA, HHS).
Hillier (Consensus): Corrected Na = Measured Na + 0.024 × (Glucose [mg/dL] - 100)
Katz (Historical): Corrected Na = Measured Na + 0.016 × (Glucose [mg/dL] - 100)
Published Clinical Benchmark Cases
Clinical Parameters & Inputs
Unit: mEq/L
mEq/L
Unit: mg/dL
mg/dL
Hillier demonstrated that 2.4 mEq/L per 100 mg/dL rise is more accurate, especially when glucose > 400 mg/dL.
Computed OutputEunatremic (Normal Effective Osmotic Sodium)
140mEq/L
Diagnostic Interpretation
Corrected Sodium is NORMAL (140 mEq/L). The observed hyponatremia is entirely translocational due to osmotic water shifting into plasma. Sodium levels will normalize as hyperglycemia resolves with insulin therapy.
Calculation Breakdown
Excess Glucose Above 100 mg/dL
600 - 100 =500 mg/dL
Hillier (2.4 factor) Corrected Sodium
128 + (0.024 × 500) =140 mEq/L
Katz (1.6 factor) Corrected Sodium
128 + (0.016 × 500) =136 mEq/L
Clinical Decision Pearls
- In diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS), monitored sodium replacement strategy is guided by the CORRECTED sodium, not measured sodium.
- If corrected sodium is high (> 145 mEq/L) or normal, switch initial fluid from 0.9% normal saline to 0.45% half-normal saline once hemodynamic stability is achieved.
Limitations & Confounders
- Does not account for pseudohyponatremia caused by severe hypertriglyceridemia or paraproteinemia on indirect ISE laboratory analyzers.
Evidence & Citations
- Hillier TA, et al. Extreme hyperglycemia: how to calculate serum sodium. Am J Med. 1999;106(4):399-403.
- Katz MA. Hyperglycemia-induced hypo-osmolar state. N Engl J Med. 1973;289(16):843-848.