What is the treatment for a patient with severe hyponatremia (sodium level of 118 mEq/L) who is symptomatic?

Management of Severe Symptomatic Hyponatremia (Na 118 mEq/L)

For a patient with severe symptomatic hyponatremia (Na 118 mEq/L), immediate treatment with 3% hypertonic saline is required, with a target correction of 4-6 mEq/L in the first 24 hours, not exceeding 8 mEq/L in 24 hours to prevent osmotic demyelination syndrome. 1

Initial Assessment and Management

1. Determine severity of symptoms:

   • Severe symptoms (seizures, altered consciousness, respiratory distress): Require immediate intervention
   • Moderate symptoms (nausea, headache, confusion): Require prompt but less aggressive correction
   • Mild symptoms (weakness, mild cognitive deficits): Allow for more gradual correction

2. Volume status assessment:

   • Hypovolemic: Signs of dehydration, orthostatic hypotension
   • Euvolemic: No signs of dehydration or fluid overload
   • Hypervolemic: Edema, ascites, fluid overload

Treatment Protocol for Symptomatic Severe Hyponatremia

Immediate Management

• Transfer to ICU with close monitoring (sodium levels every 2 hours) 1
• Administer 3% hypertonic saline for severe symptomatic cases 1, 2
  • Initial bolus: 100-150 mL of 3% hypertonic saline 3
  • Target correction: 4-6 mEq/L over first 6 hours or until severe symptoms resolve 1
  • Maximum correction: 8 mEq/L in 24 hours to prevent osmotic demyelination syndrome (ODS) 4, 1

Monitoring During Treatment

• Check serum sodium every 2 hours initially 1
• Monitor for signs of overcorrection (>8 mEq/L in 24 hours) 4, 1
• If sodium rises too rapidly (>0.5 mEq/L/hour), consider administering desmopressin to prevent further water losses 1, 5

Special Considerations

High-Risk Patients for ODS

Patients with the following risk factors require more conservative correction targets (maximum 4-6 mEq/L per day, not exceeding 8 mEq/L in 24 hours) 4, 1:

• Advanced liver disease
• Alcoholism
• Severe malnutrition
• Severe metabolic derangements (hypophosphatemia, hypokalemia, hypoglycemia)
• Low cholesterol
• Prior encephalopathy

Ongoing Management After Initial Correction

1. For hypovolemic hyponatremia:

   • After initial stabilization with hypertonic saline, transition to isotonic (0.9%) saline 1
   • Discontinue diuretics if applicable 1

2. For euvolemic hyponatremia:

   • Implement fluid restriction (<1-1.5 L/day) 1
   • Consider salt supplementation (3g/day) if needed 1
   • For SIADH, consider tolvaptan or urea as second-line therapy after initial stabilization 3

3. For hypervolemic hyponatremia:

   • Fluid restriction (<1L/day) 4, 1
   • Consider albumin infusion for severe hyponatremia (<120 mEq/L) 4

Important Cautions

• Never exceed correction rates of 8 mEq/L in 24 hours to prevent osmotic demyelination syndrome 4, 1
• Tolvaptan (vasopressin V2 receptor antagonist) should only be initiated in a hospital setting with close sodium monitoring, and not used for more than 30 days due to risk of liver injury 1, 6
• Patients requiring urgent intervention to treat serious neurological symptoms should not be treated with tolvaptan tablets 6

Follow-up Care

• Continue monitoring serum sodium levels daily until stable 1
• Check weight daily to assess fluid status 1
• Evaluate for symptoms of electrolyte imbalance (weakness, confusion, muscle cramps) 1
• Educate patient on symptoms of electrolyte imbalance to report 1

By following this protocol, you can safely correct severe symptomatic hyponatremia while minimizing the risk of osmotic demyelination syndrome, which can result in serious neurological sequelae including dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma, or death 4, 6.