What is the treatment for hyponatremia (low sodium levels)?

Treatment of Hyponatremia

The treatment of hyponatremia should be tailored to the underlying cause, severity, chronicity, and volume status of the patient, with fluid restriction and correction of underlying causes being first-line approaches for most cases. 1

Classification and Initial Assessment

Treatment depends on proper classification of hyponatremia:

1. By volume status:

   • Hypovolemic hyponatremia
   • Euvolemic hyponatremia
   • Hypervolemic hyponatremia

2. By severity:

   • Mild (126-135 mEq/L)
   • Moderate (120-125 mEq/L)
   • Severe (<120 mEq/L)

3. By chronicity:

   • Acute (developed within 48 hours)
   • Chronic (developed over >48 hours)

4. By symptoms:

   • Asymptomatic
   • Symptomatic (nausea, headache, confusion)
   • Severely symptomatic (seizures, coma)

Treatment Algorithm Based on Volume Status

1. Hypovolemic Hyponatremia

• First step: Discontinue diuretics and/or laxatives 1
• Treatment: Fluid resuscitation with 5% IV albumin or crystalloid (preferentially lactated Ringer's solution) 1
• Common causes: Excessive diuretic use, dehydration, third-spacing

2. Hypervolemic Hyponatremia (e.g., cirrhosis, heart failure)

• For mild hyponatremia (126-135 mEq/L):

  • Monitoring and water restriction only 1

• For moderate hyponatremia (120-125 mEq/L):

  • Water restriction to 1,000 mL/day
  • Cessation of diuretics 1

• For severe hyponatremia (<120 mEq/L):

  • More severe water restriction
  • Albumin infusion 1
  • Consider vasopressin receptor antagonists (vaptans) for short-term use (≤30 days) 1

3. Euvolemic Hyponatremia (e.g., SIADH)

• Treatment: Based on specific underlying cause 1
• Options:
  • Fluid restriction
  • Consider vasopressin receptor antagonists for short-term use 1, 2

Special Considerations for Symptomatic Hyponatremia

Severely Symptomatic Hyponatremia (seizures, coma)

• Emergency treatment: Hypertonic (3%) saline 1
• Goal rate of correction:
  • For patients with average risk of osmotic demyelination syndrome (ODS): 4-8 mEq/L per day, not exceeding 10-12 mEq/L in 24 hours 1
  • For high-risk patients (advanced liver disease, alcoholism, malnutrition): 4-6 mEq/L per day, not exceeding 8 mEq/L in 24 hours 1

Risk of Osmotic Demyelination Syndrome (ODS)

• High-risk factors: Advanced liver disease, alcoholism, severe hyponatremia, malnutrition, metabolic derangements, low cholesterol, prior encephalopathy 1
• If overcorrection occurs: Consider relowering with electrolyte-free water or desmopressin 1

Pharmacologic Options

Vasopressin Receptor Antagonists (Vaptans)

• Indications: Short-term treatment of hypervolemic or euvolemic hyponatremia 2
• Limitations:
  • Should be used with caution and only for short term (≤30 days) 1
  • Must be initiated in a hospital setting 2
  • Not for use in hypovolemic hyponatremia 2
  • Risk of too rapid correction of sodium 2

Albumin Infusion

• Evidence: Associated with improvement in hyponatremia in patients with cirrhosis 1
• Indication: Severe hyponatremia (<120 mEq/L) in cirrhotic patients 1

Pitfalls and Caveats

1. Avoid too rapid correction: Risk of osmotic demyelination syndrome, especially in chronic hyponatremia 1

2. Fluid restriction challenges: While commonly recommended, fluid restriction alone is often ineffective in improving serum sodium levels but may prevent further decreases 1

3. Monitoring requirements: Frequent monitoring of serum sodium is essential during correction, especially in the first 24-48 hours 1, 2

4. Hypertonic saline risks: While effective for severe symptoms, it can worsen volume overload and ascites in patients with cirrhosis 1

5. Diuretic considerations: In hypervolemic states, diuretics may need to be discontinued initially but may be required later to manage volume overload 1

By following this structured approach based on volume status, severity, and symptoms, clinicians can effectively manage hyponatremia while minimizing the risk of complications from either the condition itself or its treatment.