A 60-year-old man with small cell lung cancer develops confusion and a seizure. Serum sodium is 108 mEq/L, urine osmolality 550 mOsm/kg, urine sodium 80 mEq/L, and euvolaemia is confirmed. What is the most appropriate immediate management?
- A Fluid restriction of 800 mL/day alone
- B 100 mL boluses of 3% hypertonic saline with close monitoring, limiting correction to 8 to 10 mEq/L in 24 hours ✓
- C Demeclocycline therapy
- D Rapid correction with isotonic saline to reach 130 mEq/L within 12 hours
Correct answer: B. 100 mL boluses of 3% hypertonic saline with close monitoring, limiting correction to 8 to 10 mEq/L in 24 hours
Explanation
Symptomatic severe hyponatraemia demands hypertonic saline in small boluses, but correction must be capped at 8 to 10 mEq/L per day because faster correction risks osmotic demyelination syndrome, especially with chronic hyponatraemia. Fluid restriction is too slow for seizures, and aggressive isotonic correction invites demyelination. Demeclocycline is slow acting and nephrotoxic.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.