Corrected Sodium Formula in Pediatric DKA
The corrected sodium formula for pediatric patients with diabetic ketoacidosis is: Corrected Sodium (mEq/L) = Measured Sodium + [1.6 × (Glucose - 100) ÷ 100], where glucose is measured in mg/dL. 1
Understanding the Formula
The correction factor accounts for the osmotic shift of water from the intracellular to extracellular space caused by hyperglycemia, which artificially lowers the measured serum sodium concentration 1.
- For every 100 mg/dL rise in glucose above 100 mg/dL, add 1.6 mEq/L to the measured sodium value 1
- This corrected value guides fluid selection during DKA treatment 1
Clinical Application in Fluid Management
Initial Fluid Selection (First Hour)
Begin with isotonic saline (0.9% NaCl) at 15-20 mL/kg/hour during the first hour in the absence of cardiac compromise 1. This translates to approximately 10-20 mL/kg/hour for pediatric patients 1.
- Never exceed 50 mL/kg over the first 4 hours in pediatric patients to minimize cerebral edema risk 1
Subsequent Fluid Selection (After Initial Resuscitation)
The corrected sodium value determines subsequent fluid tonicity 1:
- If corrected serum sodium is normal or elevated: use 0.45% NaCl (half-normal saline) at 4-14 mL/kg/hour 1
- If corrected serum sodium is low: continue 0.9% NaCl at 4-14 mL/kg/hour 1
Transition to Dextrose-Containing Fluids
When plasma glucose reaches 250 mg/dL, switch to 5% dextrose with 0.45-0.75% NaCl, with saline concentration adjusted based on corrected serum sodium levels 1. The goal is maintaining glucose between 150-200 mg/dL while continuing insulin until ketoacidosis resolves (pH >7.3, bicarbonate ≥18 mEq/L) 1.
Critical Monitoring Parameters
- The induced change in serum osmolality must not exceed 3 mOsm/kg/hour to prevent cerebral edema 1
- Monitor serum electrolytes, glucose, BUN, creatinine every 2-4 hours 1
- Recalculate corrected sodium with each laboratory draw to guide ongoing fluid selection 1
Potassium Management Considerations
Always add 20-30 mEq/L potassium (2/3 KCl and 1/3 KPO4) to IV fluids once renal function is confirmed and serum K+ falls below 5.5 mEq/L 1. However, if serum K+ is <3.3 mEq/L, delay insulin therapy until potassium is corrected, as insulin will further lower potassium levels 1.
Evidence Regarding Fluid Tonicity
Research comparing different fluid strategies shows important nuances 2, 3, 4:
- Both 0.9% saline and 3% saline were equally effective for hemodynamic improvement and acidosis resolution, but 3% saline did not prevent cerebral edema and caused hypernatremia and hyperchloremic acidosis 2
- Exclusive use of 0.9% saline throughout recovery caused significant hyperchloremia leading to non-anion gap acidosis, prolonging insulin infusion duration and PICU length of stay 3
- Exclusive use of 0.45% saline resulted in significant decreases in corrected serum sodium 3
- Sodium concentration in rehydration fluids behaves as an independent factor influencing serum sodium trends positively during DKA rehydration 4
Common Pitfalls to Avoid
- Never use uncorrected sodium values to guide fluid selection—this leads to inappropriate hypotonic fluid administration in patients with pseudohyponatremia from hyperglycemia 1
- Never allow osmolality to decrease faster than 3 mOsm/kg/hour—this causes cerebral edema, especially in children 1
- Never add potassium to IV fluids before confirming adequate renal function and urine output (≥0.5 mL/kg/hour) 1
- Never use standard adult DKA fluid protocols in pediatric patients without modification—children require more conservative fluid resuscitation 1