What is the treatment for severe hyponatremia?

Treatment of Severe Hyponatremia

For severe hyponatremia, treatment should begin with hypertonic 3% saline, with the correction rate limited to 8 mEq/L per 24-hour period in high-risk patients to prevent osmotic demyelination syndrome. 1

Classification and Assessment

Hyponatremia is classified based on serum sodium levels:

• Mild: 130-135 mEq/L
• Moderate: 125-129 mEq/L
• Severe: <125 mEq/L 1

Before initiating treatment, assess:

• Symptom severity (confusion, headache, nausea, seizures, coma)
• Volume status (hypovolemic, euvolemic, hypervolemic)
• Acuity of onset (acute: <48 hours; chronic: >48 hours)
• Underlying cause (SIADH, medications, heart failure, cirrhosis)

Treatment Algorithm for Severe Hyponatremia

1. Life-threatening symptoms (seizures, coma, cardiorespiratory distress)

• Administer hypertonic 3% saline IV as boluses 2, 1
• Goal: Increase serum sodium by 4-6 mEq/L within 1-2 hours to reverse severe symptoms 3
• Do not exceed correction limit of 10 mEq/L in first 24 hours 3
• Monitor sodium levels every 2-4 hours during active correction 1

2. Symptomatic but not life-threatening

• For euvolemic hyponatremia (e.g., SIADH):

  • First-line: Fluid restriction (<1 L/day) 1
  • Consider hypertonic 3% saline if symptoms persist or sodium <120 mEq/L 2

• For hypovolemic hyponatremia:

  • Fluid resuscitation with isotonic saline or 5% albumin 1
  • Discontinue diuretics if applicable 1

• For hypervolemic hyponatremia (heart failure, cirrhosis):

  • Fluid restriction (<1 L/day) 1
  • Consider vasopressin receptor antagonists (vaptans) in appropriate patients 1, 4

3. Asymptomatic severe hyponatremia

• Treat underlying cause
• Fluid restriction may be sufficient 5
• Monitor sodium levels closely

Correction Rate Guidelines

• Standard correction limit: 10 mEq/L in first 24 hours 3
• High-risk patients (alcoholism, malnutrition, liver disease): limit to 8 mEq/L per 24 hours 1
• Target correction rate: 0.5 mEq/L per hour for chronic hyponatremia 5
• Goal: Reach mildly hyponatremic range (125-130 mEq/L) initially, not normal levels 5, 6

Rapid Intermittent Bolus vs. Slow Continuous Infusion

Recent evidence suggests that rapid intermittent bolus (RIB) therapy may be preferable to slow continuous infusion (SCI) for symptomatic hyponatremia:

• Similar overcorrection risk between methods (17.2% vs 24.2%) 7
• RIB showed lower incidence of requiring relowering treatment (41.4% vs 57.1%) 7
• RIB was more effective in achieving target correction rate within 1 hour 7

Prevention of Overcorrection

• Monitor sodium levels every 2-4 hours during active correction 1
• If correction is too rapid, consider administering dextrose 5% in water (D5W) or desmopressin to prevent further rise 3
• Avoid correction to normonatremia or hypernatremia in the acute setting 6

Pharmacologic Options

• Vasopressin receptor antagonists (vaptans):
  • Consider for euvolemic or hypervolemic hyponatremia 1, 4
  • Must be initiated in hospital setting 1
  • Limited to 30 days due to risk of liver injury 1
  • May cause overly rapid correction and increased thirst 3

Common Pitfalls to Avoid

1. Correcting sodium too rapidly (risk of osmotic demyelination syndrome)
2. Failing to identify and treat the underlying cause
3. Not monitoring sodium levels frequently enough during correction
4. Aiming for normal sodium levels in the acute setting
5. Not adjusting correction rates for high-risk patients
6. Overlooking concurrent electrolyte abnormalities (especially hypokalemia and hypomagnesemia)

By following these guidelines, clinicians can effectively manage severe hyponatremia while minimizing the risk of complications such as osmotic demyelination syndrome.