Osmotic demyelination syndrome is a risk associated with rapid correction of which electrolyte abnormality?

Osmotic demyelination syndrome is a risk associated with rapid correction of which electrolyte abnormality?

• A. Hypernatremia
• B. Hypokalemia
• C. Hyponatremia
• D. Hypercalcemia

Answer: (C)

Rapid correction of low serum sodium is dangerous because the brain adapts to hyponatremia by losing intracellular osmolites to prevent swelling. If we raise the serum sodium quickly, the extracellular environment becomes hypertonic relative to the brain, and water rushes out of brain cells. This rapid cellular dehydration damages oligodendrocytes and causes demyelination, most notably in the central pons, known as osmotic demyelination syndrome. Because of this risk, hyponatremia must be corrected gradually, typically not exceeding about 8–12 mEq/L in 24 hours, to minimize the chance of demyelination. Rapid correction of other electrolyte abnormalities does not produce the same pattern of osmotic injury.

Rapid correction of low serum sodium is dangerous because the brain adapts to hyponatremia by losing intracellular osmolites to prevent swelling. If we raise the serum sodium quickly, the extracellular environment becomes hypertonic relative to the brain, and water rushes out of brain cells. This rapid cellular dehydration damages oligodendrocytes and causes demyelination, most notably in the central pons, known as osmotic demyelination syndrome. Because of this risk, hyponatremia must be corrected gradually, typically not exceeding about 8–12 mEq/L in 24 hours, to minimize the chance of demyelination. Rapid correction of other electrolyte abnormalities does not produce the same pattern of osmotic injury.