A 40-year-old man develops profound hyponatremia (Na+ 112 mEq/L) after marathon running; he is symptomatic with nausea and confusion. What is the appropriate correction rate to avoid osmotic demyelination syndrome (ODS)?
- A Correct Na+ by 1–2 mEq/L/hr until symptoms resolve, then slower
- B Correct Na+ by 12 mEq/L/hr to achieve rapid resolution
- C Maximum 8 mEq/L in first 24 hours and 18 mEq/L in 48 hours ✓
- D Restrict all fluids and allow spontaneous correction
Explanation
In symptomatic severe hyponatremia, the rate of correction must be controlled to prevent osmotic demyelination syndrome (ODS/CPM), which occurs with overly rapid correction. Current guidelines recommend: in acute or symptomatic cases, give 100 mL 3% hypertonic saline over 10 minutes (may repeat up to 3 times) to rapidly raise Na+ by 5 mEq/L to control symptoms. However, the total correction should not exceed 8–10 mEq/L in the first 24 hours and 18 mEq/L in 48 hours. Exercise-associated hyponatremia is due to hypotonic fluid overload, not inappropriate ADH. Fluid restriction alone is insufficient in acute symptomatic cases.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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