A 2-year-old child (weight 12 kg) with severe dehydration and a serum sodium of 168 mEq/L is being rehydrated. The most important principle governing the rate of sodium correction in hypernatremic dehydration is:
- A Correct sodium by no more than 10–12 mEq/L/day to prevent cerebral edema ✓
- B Correct sodium at a rate of 1–2 mEq/L/hour to normalize within 24 hours
- C Give 3% saline to correct the hypernatremia rapidly
- D Replace deficit over 6–8 hours using hypotonic saline
Correct answer: A. Correct sodium by no more than 10–12 mEq/L/day to prevent cerebral edema
Explanation
In hypernatremic dehydration, rapid lowering of serum sodium causes water shift into brain cells (which have accumulated idiogenic osmoles), resulting in cerebral edema and seizures. The safe correction rate is a maximum of 10–12 mEq/L/day (approximately 0.5 mEq/L/hour). Rehydration should be performed gradually over 48–72 hours using isotonic or mildly hypotonic fluids. Rapid correction and 3% saline are contraindicated; the latter would worsen hypernatremia.
Reference: Ghai Essential Pediatrics, 10th ed.
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