Treatment of Hypernatremia in Children: Do NOT Use 0.2% Saline
No, 0.2% saline (hypotonic saline) should never be used in the treatment of hypernatremia in children—the correct treatment is 5% dextrose in water (D5W) or other hypotonic fluids that provide free water without additional sodium load. 1
Why 0.2% Saline is Contraindicated
- 0.2% saline still contains sodium (34 mEq/L), which worsens hypernatremia by adding more sodium to an already sodium-overloaded state. 1
- Normal saline (0.9% NaCl) has a tonicity of
300 mOsm/kg H₂O, which is 3-fold higher than typical urine osmolality in hypernatremic conditions (100 mOsm/kg H₂O), and even diluted versions like 0.2% saline provide unnecessary sodium. 1 - The fundamental principle in treating hypernatremia is providing free water to dilute the elevated serum sodium—any saline solution works against this goal. 1, 2
Correct Treatment Approach
Primary Rehydration Fluid
- Use 5% dextrose in water (D5W) as the primary rehydration fluid for hypernatremic children, as recommended by the American Academy of Pediatrics. 1
- D5W provides free water without additional sodium load, allowing gradual correction of the hyperosmolar state. 1
Fluid Rate Calculation
- Calculate initial fluid rate based on physiological maintenance requirements: 1
- First 10 kg: 100 ml/kg/24h (4 ml/kg/h)
- 10-20 kg: add 50 ml/kg/24h (2 ml/kg/h)
- Above 20 kg: add 20 ml/kg/24h (1 ml/kg/h)
Water Deficit Formula
- Water deficit = Total body water × [(Current Na⁺/Desired Na⁺) - 1], where Total body water (TBW) = 0.6 × weight in kg. 3
- The total D5W needed equals the calculated water deficit, administered over 48-72 hours depending on severity. 3, 4
Critical Correction Parameters
Rate of Sodium Reduction
- Target sodium reduction of 0.5 mmol/L per hour or 10-15 mmol/L per 24 hours maximum to avoid cerebral edema. 1
- Recent evidence from a large pediatric cohort (402 episodes) found that rapid correction (>0.5 mmol/L per hour) was not associated with greater neurological complications or mortality, though current guidelines remain conservative. 5
- The rate of rehydration is more critical than the exact composition of the rehydrating solution—too rapid correction causes cerebral edema, stupor, and convulsions. 4
Monitoring Requirements
- Check serum sodium every 2-4 hours initially during active correction. 1, 3
- Monitor for signs of cerebral edema: altered mental status, seizures, headache, increased intracranial pressure. 1
- Adjust D5W rate based on sodium measurements to ensure correction rate stays within safe limits. 3
Common Clinical Pitfalls
What NOT to Do
- Never use normal saline (0.9% NaCl) or any saline solution as primary rehydration fluid in hypernatremia—this worsens the condition. 1, 6
- Do not use 0.45% saline, which is reserved for diabetic ketoacidosis maintenance after initial resuscitation, not hypernatremia treatment. 1
- Avoid excessively rapid rehydration over less than 24 hours, which increases risk of cerebral edema and permanent neurological deficits. 4
High-Risk Scenarios
- Approximately 10-15% of children with serum sodium ≥160 mEq/L will have permanent neurological deficits, emphasizing the importance of controlled correction. 4
- Hospital-acquired hypernatremia occurs in patients with restricted access to fluids combined with ongoing free-water losses—prevention requires providing adequate free-water when mild hypernatremia (Na >145 mEq/L) develops. 7
- Breastfed infants are at high risk for severe hypernatremia from insufficient lactation and require close monitoring. 7
Special Considerations for Severe Cases
- When sodium is severely elevated (>170 mEq/L) or patients are symptomatic, hypotonic fluid replacement with D5W is necessary, with potential consideration of renal replacement therapy in extreme cases (e.g., sodium >210 mEq/L). 2, 8
- In cases of extreme hypernatremia with acute kidney injury, peritoneal dialysis combined with intravenous fluids can achieve effective sodium correction within recommended rates. 8