What is the ideal ratio of sodium correction to blood sugar (Random Blood Sugar, RBS) correction in patients with Diabetic Ketoacidosis (DKA)?

Sodium Correction Ratio in DKA

For every 100 mg/dL rise in blood glucose above 100 mg/dL, add 1.6 mEq/L to the measured serum sodium to calculate the corrected sodium value, which guides fluid therapy decisions in DKA management. 1, 2

The Correction Formula

The standard correction ratio is:

• Corrected Na+ = Measured Na+ + 1.6 × ([Glucose in mg/dL - 100]/100) 1, 2
• This means for each 100 mg/dL glucose elevation above 100 mg/dL, sodium increases by 1.6 mEq/L 1

Clinical Application Algorithm

Step 1: Calculate Corrected Sodium

• Measure serum sodium and blood glucose on presentation 1
• Apply the 1.6 mEq/L correction factor per 100 mg/dL glucose elevation 1, 2
• Example: If measured Na+ is 130 mEq/L and glucose is 500 mg/dL, corrected Na+ = 130 + 1.6 × [(500-100)/100] = 136.4 mEq/L 2

Step 2: Use Corrected Sodium to Guide Fluid Choice

• If corrected sodium is normal or elevated: Use 0.45% NaCl (half-normal saline) at 4-14 ml/kg/h 1, 2
• If corrected sodium is low: Use 0.9% NaCl (normal saline) at 4-14 ml/kg/h 1, 2
• This decision occurs after the initial resuscitation with 15-20 ml/kg/h of 0.9% NaCl in the first hour 1

Critical Distinction: Two Different Sodium Values for Two Different Purposes

Corrected Sodium (for fluid selection):

• Used to determine which IV fluid to administer 1, 2
• Accounts for the dilutional effect of hyperglycemia on sodium 1

Measured Sodium (for osmolality calculation):

• Use the measured (uncorrected) sodium for calculating effective serum osmolality 2
• Formula: Effective osmolality = 2[measured Na+] + glucose (mg/dL)/18 1, 2
• This monitors treatment progress and severity assessment 2

Monitoring the Correction Rate

• Osmolality should decrease by no more than 3 mOsm/kg/h to prevent cerebral edema 1, 2
• Recheck electrolytes every 2-4 hours during active treatment 1
• Fluid replacement should correct estimated deficits within 24 hours 1

Common Pitfalls to Avoid

Using corrected sodium for osmolality calculations: This is incorrect—always use measured sodium for osmolality monitoring 2

Overly rapid correction: Decreasing osmolality faster than 3 mOsm/kg/h increases cerebral edema risk, particularly in pediatric patients 1, 2, 3

Ignoring the corrected sodium when selecting fluids: Using inappropriate fluid tonicity can worsen hyponatremia or hypernatremia 1, 2, 4

Switching to hypotonic fluids too early: The corrected sodium must be normal or elevated before using 0.45% NaCl 1

Special Consideration: Hypernatremia in DKA

While hyponatremia is more common, hypernatremia can occur in DKA 4. In these cases:

• Initial bolus with isotonic saline (0.9% NaCl) is still appropriate 4
• Continue with half-normal saline (0.45% NaCl) for ongoing correction 4
• Monitor sodium closely as glucose falls, since the corrected sodium will rise further as hyperglycemia resolves 4