Corrected Sodium Calculation for Glucose 714 mg/dL
Add approximately 9.8 mEq/L to the measured sodium value to obtain the corrected (true) sodium when glucose is 714 mg/dL. 1
The Correction Formula
The American Diabetes Association guidelines establish the standard correction factor: for each 100 mg/dL glucose above 100 mg/dL, add 1.6 mEq to the measured sodium value. 1
Step-by-Step Calculation
- Glucose elevation above baseline: 714 - 100 = 614 mg/dL 2
- Number of 100 mg/dL increments: 614 ÷ 100 = 6.14 2
- Sodium correction needed: 6.14 × 1.6 = 9.8 mEq/L 1
Example: If the measured sodium is 135 mEq/L, the corrected (true) sodium would be 135 + 9.8 = 144.8 mEq/L 2
Clinical Significance of the Corrected Sodium
The corrected sodium determines your choice of intravenous fluids and predicts the degree of hypertonicity from osmotic diuresis. 2, 3
Fluid Selection Algorithm
- If corrected sodium is normal or elevated (≥135 mEq/L): Use 0.45% NaCl at 4-14 mL/kg/h 1
- If corrected sodium is low (<135 mEq/L): Use 0.9% NaCl at 4-14 mL/kg/h 1
- After initial resuscitation with isotonic saline (15-20 mL/kg/h in first hour): Switch to the appropriate fluid based on corrected sodium 1
Why This Matters for Patient Outcomes
The corrected sodium reveals the true degree of water deficit from osmotic diuresis that occurred before presentation. 3 In hyperosmolar hyperglycemic state (HHS), mean corrected sodium reaches 160.8 mEq/L, indicating severe hypernatremia masked by hyperglycemia. 3 This profound water deficit requires aggressive hypotonic fluid replacement to prevent neurological complications and death. 4, 5, 6
Critical Monitoring During Treatment
Monitor corrected sodium every 2-4 hours during treatment because it changes as osmotic diuresis continues and fluids are replaced. 1, 3
Rate of Correction Limits
- Osmolality decrease must not exceed 3 mOsm/kg/h to prevent cerebral edema 1, 2, 7, 4
- Sodium correction should not exceed 8-10 mEq/L per day to avoid osmotic demyelination 7, 6
Common Pitfall to Avoid
Do NOT use the corrected sodium for calculating effective osmolality—always use the measured sodium for osmolality calculations. 2 The formula for effective osmolality is: 2[measured Na] + glucose/18. 1, 2 This distinction is crucial: corrected sodium guides fluid therapy, while measured sodium assesses severity and monitors treatment progress. 2
Additional Management Considerations
Once renal function is confirmed, add 20-30 mEq/L potassium to IV fluids (2/3 KCl and 1/3 KPO4). 1, 7 Hyperglycemic crises cause total body potassium deficits of 3-5 mEq/kg in DKA and 5-15 mEq/kg in HHS despite normal or elevated initial serum levels. 1
Begin insulin infusion at 0.1 units/kg/h only after initial fluid resuscitation and potassium >3.3 mEq/L. 1, 4 In HHS specifically, delay insulin until osmolality stops falling with fluid replacement alone, unless significant ketonemia is present. 4