How should I manage a patient with severe hyponatremia?

Management of Severe Hyponatremia (Sodium 3.4 mmol/L)

A sodium level of 3.4 mmol/L represents a critical medical emergency requiring immediate aggressive correction with hypertonic saline to prevent cerebral edema, seizures, and death. 1

Initial Assessment and Treatment

• Severe hyponatremia (Na <125 mmol/L) with neurological symptoms requires emergency infusion of 3% hypertonic saline 1, 2
• For patients with severe symptomatic hyponatremia, administer 100-150 mL bolus of 3% hypertonic saline 1, 3
• Target initial correction of 6 mmol/L over 6 hours or until severe symptoms resolve 1
• Total correction should not exceed 8-10 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 4
• Monitor serum sodium every 4-6 hours during initial correction 1

Hospital-Based Management

• Initiate treatment in a hospital setting where serum sodium can be closely monitored 4
• Too rapid correction (>12 mEq/L/24 hours) can cause osmotic demyelination resulting in dysarthria, mutism, dysphagia, lethargy, seizures, coma and death 4
• In susceptible patients (those with malnutrition, alcoholism, or advanced liver disease), slower rates of correction are advisable 4

Ongoing Management After Initial Stabilization

• After initial emergency correction, determine the underlying cause of hyponatremia to guide further management 2
• For hypovolemic hyponatremia: administer normal saline infusions 2
• For euvolemic hyponatremia: consider fluid restriction, salt tablets, or vaptans 2
• For hypervolemic hyponatremia: treat the underlying cause (heart failure, cirrhosis) and restrict free water 2

Medication Considerations

• Tolvaptan may be considered for euvolemic or hypervolemic hyponatremia once the patient is stabilized 4, 3
• Tolvaptan should only be initiated in a hospital setting with close monitoring of serum sodium 4
• Do not use tolvaptan in patients with hypovolemic hyponatremia 4
• Monitor for hyperkalemia when using oral sodium supplements, especially in patients with renal impairment 1

Avoiding Complications

• Never exceed correction of 8 mmol/L in 24 hours for chronic hyponatremia 1, 4
• Monitor for signs of osmotic demyelination syndrome, which can occur with too rapid correction 4
• After initial correction, if overcorrection is occurring, consider administering hypotonic fluids or desmopressin 3
• Avoid fluid restriction during the first 24 hours of therapy with tolvaptan 4

Special Considerations

• In patients with cirrhosis and hyponatremia, fluid restriction to 1-1.5 L/day is recommended for severe hyponatremia 5
• In neurosurgical patients, hypertonic saline should be limited to severely symptomatic cases 1
• The risk of overcorrection is higher in severely symptomatic patients; monitor diuresis closely as it correlates with sodium overcorrection 1

Remember that a sodium level of 3.4 mmol/L is incompatible with life and likely represents a critical laboratory error that requires immediate verification before treatment. If confirmed, this represents an extreme medical emergency requiring immediate intensive care management.