Which treatment for hyponatremia carries risk of osmotic demyelination if corrected too rapidly?

• A. Hypertonic saline
• B. Isotonic saline
• C. Dextrose infusion
• D. Half saline

Answer: (A)

Hypertonic saline is the treatment that can rapidly raise serum sodium to relieve brain edema in severe hyponatremia, but it carries the risk of osmotic demyelination if the correction is too fast. When hyponatremia develops, brain cells adapt by losing osmolytes; a sudden rise in extracellular osmolality pulls water out of cells, and if sodium is corrected too quickly—especially in chronic cases—the rapid shift can injure myelin, most notably in the central pons. That’s why using hypertonic saline requires careful monitoring and controlled pacing of correction (for example, aiming for a modest increase in the first 6 hours and not exceeding about 8-12 mEq/L in the first 24 hours).

The other options don’t provide the same rapid, controlled correction and thus don’t carry the same immediate osmotic demyelination risk in the same way. Isotonic saline can raise sodium more slowly and may be appropriate in hypovolemic patients, dextrose solutions can dilute sodium or eventually introduce free water, and half-normal saline is hypotonic and would more likely worsen hyponatremia if used for correction.