What is the inpatient treatment for severe hyponatremia (low sodium level)?

Inpatient Treatment for Severe Hyponatremia (Sodium 122)

For a patient with severe hyponatremia (sodium 122 mEq/L), treatment should be guided by symptom severity, with hypertonic (3%) saline as the cornerstone of management for symptomatic patients, correcting sodium by 6 mmol/L over 6 hours or until severe symptoms resolve, with total correction not exceeding 8 mmol/L in 24 hours. 1, 2

Initial Assessment and Classification

First, determine the patient's:

1. Symptom severity:

   • Severe symptoms: Mental status changes, seizures, coma
   • Mild symptoms: Nausea, vomiting, headache, weakness
   • Asymptomatic

2. Volume status:

   • Hypovolemic (CSW, diuretics, adrenal insufficiency)
   • Euvolemic (SIADH)
   • Hypervolemic (heart failure, cirrhosis)

3. Duration: Acute (<48 hours) vs. chronic (>48 hours)

Treatment Algorithm Based on Symptoms

For Severe Symptoms (Mental status changes, seizures)

• Transfer to ICU for close monitoring
• Administer 3% hypertonic saline 1, 2
  • Goal: Correct sodium by 6 mmol/L in first 6 hours or until severe symptoms improve
  • Monitor sodium levels every 2 hours
  • Calculate sodium deficit: Desired increase in Na (mEq) × (0.5 × ideal body weight)
  • Total correction should not exceed 8 mmol/L in 24 hours
• Monitor fluid intake/output and daily weight
• For CSW: Consider adding fludrocortisone for 7 days 1

For Mild Symptoms (Nausea, vomiting, headache) or Na <120 mEq/L

• Transfer to intermediate care unit
• Monitor sodium every 4 hours
• For SIADH: Fluid restriction to 1 L/day 1, 2
• For CSW: Normal saline infusion 1
• Monitor daily sodium levels

For Asymptomatic Hyponatremia

• For SIADH: Fluid restriction (1-1.5 L/day) 2
• For CSW: Normal saline and salt tablets 1
• Daily sodium monitoring

Important Considerations

• Avoid overly rapid correction (>8-10 mmol/L/24 hours) to prevent osmotic demyelination syndrome, especially in patients with:

  • Chronic hyponatremia
  • Severe malnutrition
  • Alcoholism
  • Advanced liver disease 1, 2

• Tolvaptan may be considered for euvolemic or hypervolemic hyponatremia, but:

  • Must be initiated in hospital setting
  • Not for urgent sodium correction
  • Limited to 30 days due to liver injury risk
  • Contraindicated in hypovolemic hyponatremia 2, 3

• Discontinue causative medications if applicable

Monitoring During Treatment

• For severe symptoms: Check sodium every 2 hours initially
• For mild symptoms: Check sodium every 4 hours
• If correction exceeds 8 mmol/L in 24 hours, consider administration of hypotonic fluids or desmopressin to prevent further rapid correction 2

Common Pitfalls to Avoid

1. Fluid restriction in CSW - can worsen cerebral perfusion and increase risk of cerebral infarction 1
2. Overly rapid correction - can lead to osmotic demyelination syndrome with devastating neurological consequences 1, 2
3. Treating without identifying underlying cause - different etiologies require different approaches
4. Failing to recognize acute vs. chronic hyponatremia - acute hyponatremia may require more aggressive correction 1
5. Using tolvaptan for urgent correction - not indicated for emergency treatment 3

By following this structured approach based on symptom severity and underlying cause, the management of severe hyponatremia can be optimized to improve outcomes while minimizing the risk of complications.