How to manage severe hyponatremia?

Management of Severe Hyponatremia (Sodium 112 mEq/L)

For severe hyponatremia with sodium of 112 mEq/L, immediate treatment with 3% hypertonic saline is recommended to increase serum sodium by 4-6 mEq/L within 1-2 hours, with a maximum correction of 8 mEq/L in 24 hours to avoid osmotic demyelination syndrome. 1

Initial Assessment and Classification

First, determine the volume status and chronicity of hyponatremia:

• Volume status assessment: Hypovolemic, euvolemic, or hypervolemic 2
• Chronicity: Acute (<48 hours) or chronic (>48 hours) 2
• Symptom severity: Mild (nausea, weakness), moderate (confusion), or severe (seizures, coma) 1, 3

Laboratory workup should include:

• Serum osmolality, electrolytes, BUN, creatinine
• Urine sodium, osmolality, specific gravity
• Additional tests: CBC, liver function, TSH 1

Treatment Algorithm Based on Symptoms and Volume Status

1. Severe Symptomatic Hyponatremia (seizures, coma, respiratory distress)

• Immediate intervention required:
  • Administer 3% hypertonic saline to increase serum sodium by 4-6 mEq/L within 1-2 hours 1
  • Initial bolus: 100-150 mL of 3% saline over 10-20 minutes, may repeat if symptoms persist 3
  • Monitor serum sodium every 2-4 hours initially 1
  • Maximum correction: 8 mEq/L in 24 hours to avoid osmotic demyelination syndrome 2, 1

2. Treatment Based on Volume Status

Hypovolemic Hyponatremia:

• Discontinue diuretics/laxatives 2
• Fluid resuscitation: 0.9% normal saline or 5% IV albumin 2
• Monitor: Serum sodium every 4-6 hours until stable 1

Euvolemic Hyponatremia:

• Fluid restriction: 1000 mL/day 2, 1
• Salt tablets: Consider oral supplementation (5-10 mmol/kg/day) 1
• For refractory cases: Consider vasopressin antagonists (vaptans) for short-term use 2, 4

Hypervolemic Hyponatremia:

• Fluid restriction: More severe restriction (<1000 mL/day) 2
• Discontinue diuretics/laxatives that may be contributing 2
• Albumin infusion: Particularly beneficial in cirrhosis with severe hyponatremia 2, 1
• Treat underlying cause: Heart failure, cirrhosis, etc. 1

Special Considerations

Correction Rate

• Standard correction rate: Maximum 8 mEq/L in 24 hours 2, 1
• High-risk patients (alcoholism, malnutrition, liver disease): Consider slower correction (4-6 mEq/L in 24 hours) 2
• Monitor closely: Check serum sodium every 2-4 hours during active correction 1

Osmotic Demyelination Syndrome (ODS) Prevention

• Risk factors: Chronic hyponatremia, alcoholism, liver disease, malnutrition 2, 4
• Warning signs: Dysarthria, dysphagia, altered mental status, quadriparesis 2
• If overcorrection occurs: Consider administration of hypotonic fluids or desmopressin to re-lower sodium 1

Use of Vasopressin Antagonists (Vaptans)

• Consider for: Euvolemic or hypervolemic hyponatremia refractory to conventional therapy 2, 4
• Contraindicated in: Hypovolemic hyponatremia 1
• Caution: Not recommended for long-term use in cirrhosis due to safety concerns 1, 4
• Monitor: Risk of overly rapid correction and hypernatremia 4

Ongoing Management

• Follow-up monitoring: Severe abnormalities require follow-up within 24-48 hours 1
• Identify and address underlying cause: SIADH, medications, endocrine disorders 1, 3
• Medication review: Assess for medications that can cause hyponatremia (diuretics, antidepressants, antipsychotics, antiepileptics) 1

Common Pitfalls to Avoid

1. Overly rapid correction: Can lead to osmotic demyelination syndrome 2, 1
2. Inadequate monitoring: Serum sodium must be checked frequently during correction 1
3. Inappropriate fluid administration: Avoid hypotonic fluids in symptomatic hyponatremia 1
4. Failure to identify underlying cause: Treatment should address the root cause 1, 3
5. Using vaptans in hypovolemic patients: Can worsen volume depletion 1, 4

By following this structured approach based on symptom severity and volume status, severe hyponatremia can be managed effectively while minimizing the risk of complications.