A 3-year-old child with severe hypernatremic dehydration (Na+ 168 mEq/L) is being rehydrated. Over what period should sodium be corrected, and what is the maximum safe rate of serum sodium reduction?
- A Rapid correction over 6 hours; no rate restriction necessary
- B Correction over 24 hours at 1 mEq/L/hour rate
- C Slow correction over 48–72 hours; maximum drop of 0.5 mEq/L/hour (12 mEq/L/day) ✓
- D Free water boluses of 20 mL/kg every 30 minutes until Na < 150 mEq/L
Correct answer: C. Slow correction over 48–72 hours; maximum drop of 0.5 mEq/L/hour (12 mEq/L/day)
Explanation
In hypernatremic dehydration, the brain generates idiogenic osmoles (taurine, myoinositol) to maintain cell volume against the hyperosmolar state. Rapid correction of hypernatremia reverses this osmotic gradient too quickly, causing water shift into brain cells resulting in cerebral edema and potentially fatal herniation. Safe correction mandates reducing serum sodium at no more than 0.5 mEq/L/hour (10–12 mEq/L/day), over 48–72 hours, using hypotonic fluids. Free water boluses cause dangerous osmotic shifts and are contraindicated.
Reference: Ghai Essential Pediatrics, 10th ed.
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Written and medically reviewed by the StethoPrep medical team.