Rapid correction of hypernatremia can lead to which complication?

• A. Seizures
• B. Hyperkalemia
• C. Hypotension
• D. Cerebral edema

Answer: (D)

Rapid correction of hypernatremia can cause cerebral edema because the brain adapts to a hyperosmolar environment by accumulating osmolytes to prevent excessive cell shrinkage. If serum sodium is lowered quickly, the extracellular osmolality falls faster than the brain can readjust, and water rushes into brain cells. This influx leads to swelling of brain tissue, which can cause significant neurologic complications or even herniation. Therefore, hypernatremia is corrected slowly to allow the brain to re-equilibrate safely.