What is the most appropriate management for a patient with severe hyponatremia (low sodium level) and symptoms of confusion and seizure?

Management of Severe Symptomatic Hyponatremia with Seizure

Administer 3% hypertonic saline 100 mL IV immediately for this patient with severe symptomatic hyponatremia (sodium 122 mEq/L) presenting with seizure and altered mental status after MDMA ingestion. 1, 2, 3

Rationale for Hypertonic Saline

This 20-year-old presents with severe symptomatic hyponatremia requiring emergency intervention:

• Seizure activity indicates hyponatremic encephalopathy, a medical emergency 1, 3
• Altered mental status (obtunded, confused, slow to respond) represents severe neurological symptoms 1, 2
• Sodium 122 mEq/L meets criteria for severe hyponatremia (<125 mEq/L) 1, 2
• MDMA-induced SIADH is the likely etiology, causing acute water retention 3, 4

The goal is to increase sodium by 4-6 mEq/L over the first 1-2 hours or until seizures resolve, which typically reverses acute cerebral edema 1, 3, 5

Administration Protocol

• Give 100 mL of 3% hypertonic saline as IV bolus over 10 minutes 1, 5
• Can repeat up to 3 times at 10-minute intervals if severe symptoms persist 1
• Check sodium level every 2 hours during initial correction 1
• Stop hypertonic saline once symptoms improve or sodium increases by 6 mEq/L 1, 3

Critical Safety Limits

Total correction must not exceed 8 mEq/L in the first 24 hours to prevent osmotic demyelination syndrome 1, 2, 3, 5

• This patient likely has acute hyponatremia (<48 hours duration) from MDMA use, which carries lower risk of osmotic demyelination than chronic hyponatremia 1, 6
• However, correction limits still apply as duration cannot be definitively determined 1, 5
• After initial 4-6 mEq/L increase, switch to slower correction with monitoring every 4-6 hours 1

Why Other Options Are Incorrect

5% dextrose in water (D5W) would worsen hyponatremia by providing free water without sodium 1, 2

0.9% normal saline is insufficient for severe symptomatic hyponatremia—it lacks the osmotic gradient needed to rapidly reduce cerebral edema 1, 2, 3

Potassium chloride addresses the mild hypokalemia (3.4 mEq/L) but does nothing for the life-threatening hyponatremia causing seizures 1

Oral sodium chloride tablets are inappropriate for a patient with altered mental status who cannot safely take oral medications and requires immediate IV intervention 1, 7

Additional Management Considerations

• Obtain and correct the mild hypokalemia (3.4 mEq/L) and low bicarbonate (18 mEq/L) once the patient is stabilized 1
• Monitor respiratory status closely given respirations of 8/minute—may require ventilatory support 2
• Address hyperthermia (temperature 100.4°F) which can occur with MDMA toxicity 2
• After symptom resolution, transition to fluid restriction (1 L/day) if SIADH persists 1, 3

Common Pitfalls to Avoid

Do not delay treatment while pursuing diagnostic workup—severe symptomatic hyponatremia requires immediate intervention 1, 2, 3

Do not use fluid restriction alone in severely symptomatic patients—this is only appropriate for asymptomatic or mildly symptomatic chronic hyponatremia 1, 5

Do not overcorrect—if sodium increases >8 mEq/L in 24 hours, immediately switch to D5W and consider desmopressin to prevent osmotic demyelination 1

Monitor for diuresis after hypertonic saline administration, as this correlates with risk of overcorrection 7