Why must rapid correction of hyponatremia be avoided?

• A. Seizure risk
• B. Osmotic demyelination syndrome
• C. Water intoxication
• D. Hypokalemia

Answer: (B)

Rapid correction of hyponatremia is dangerous because it can cause osmotic demyelination syndrome. When the brain has adapted to chronic low sodium by lowering intracellular osmolytes, a rapid increase in serum sodium raises extracellular osmolality quickly. Water leaves brain cells, causing them to shrink and myelin to be damaged, most famously in the central pons. This demyelination can lead to severe, often irreversible neurologic deficits such as quadriparesis, dysarthria, dysphagia, and altered consciousness. To minimize this risk, sodium is raised only gradually, with careful monitoring of the rate (commonly around 4-6 mEq/L in the first 24 hours, depending on guidelines and patient factors), and strategies are used to prevent overcorrection if needed. While seizures can occur in acute hyponatremia, the principal danger of rapid correction in chronic cases is osmotic demyelination syndrome, not water intoxication or hypokalemia.