An elderly male found unresponsive in a sauna after prolonged exposure with Na 110, Cl 95, BUN 34, Cr 2.0, K 3.4, HCO3 24, Glu 78; what treatment is indicated?

• A. Administration of a hypertonic saline solution
• B. Administration of a 20 mg potassium infusion
• C. Administration of Sodium Bicarbonate
• D. Rapid fluid replacement of 50 mL/kg of balanced Lactated Ringer's solution

Answer: (A)

Severe symptomatic hyponatremia is the situation here. When serum sodium drops this low (110 mEq/L) and the patient is unresponsive, the brain is at risk from cerebral edema, and the priority is to raise serum sodium rapidly enough to relieve CNS symptoms without causing overly rapid overcorrection later.

Administer hypertonic saline (3% NaCl) in controlled boluses (for example, 100 mL IV over 10 minutes, reassess after each bolus). Repeat as needed up to about 4–6 mEq/L increase in the first few hours or until mental status improves. The goal is to improve neurologic status quickly but avoid overshoot, which could lead to osmotic demyelination. After stabilization, transition to slower correction with appropriate fluids and close electrolyte monitoring.

The other options don’t address the acute life-threatening CNS effects of severe hyponatremia: a potassium infusion is not indicated for correcting sodium, sodium bicarbonate doesn’t treat hyponatremia, and rapid isotonic fluid alone could worsen or not adequately correct the sodium level in this scenario.