🏥 USMLE Exam Prep

A 60-year-old woman with a history of small cell lung cancer presents to the emergency department with new-onset confusion and seizures. Her serum sodium is 118 mEq/L. Physical examination reveals no signs of fluid overload or dehydration. Urine osmolality is 450 mOsm/kg, and urine sodium is 50 mEq/L. What is the most appropriate immediate management?

A Fluid restriction to 1000 mL/day
B Administer hypertonic (3%) saline
C Start a vasopressin receptor antagonist (e.g., tolvaptan)
D Infuse normal saline (0.9% NaCl)

✓ Correct Answer: Option B

Symptomatic severe hyponatremia, especially with neurological symptoms like seizures, requires rapid but controlled correction with hypertonic saline to prevent cerebral edema. Fluid restriction is for mild/asymptomatic cases.

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