How to correct severe hyponatremia in the Emergency Room (ER)?

Management of Severe Hyponatremia in the Emergency Room

For severe hyponatremia (sodium <110-120 mmol/L) in the ER, administer 3% hypertonic saline with an initial goal to correct 6 mmol/L over 6 hours or until severe symptoms resolve, with total correction not exceeding 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1, 2

Initial Assessment and Classification

• Determine symptom severity: severe symptoms include mental status changes, seizures, coma; mild symptoms include nausea, vomiting, headache 2
• Assess volume status to classify as hypovolemic, euvolemic, or hypervolemic hyponatremia 2
• Check urine sodium and osmolality to help distinguish between SIADH and Cerebral Salt Wasting (CSW) 2

Treatment Based on Symptom Severity

For Severe Symptoms (Mental Status Changes, Seizures, Coma)

• Administer 3% hypertonic saline immediately 2, 3
• Initial goal: correct sodium by 6 mmol/L over 6 hours or until severe symptoms resolve 1, 2
• Maximum correction: 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 2
• Calculate sodium deficit using formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1, 2
• Transfer to ICU for close monitoring with sodium checks every 2 hours during initial correction 1, 2
• Monitor fluid intake/output and daily weight 1

For Mild Symptoms or Asymptomatic (Na <120 mmol/L)

• Transfer to intermediate care unit 1
• Monitor sodium levels every 4 hours initially 1
• Implement fluid restriction to 1 L/day, especially for SIADH 1, 2
• If no response to fluid restriction, add sodium chloride 100 mEq orally three times daily 1, 2

Treatment Based on Etiology

For SIADH

• Primary treatment is fluid restriction to 1 L/day 1, 2
• Consider additional options if no response: oral sodium supplementation, urea, or vasopressin receptor antagonists 2, 4
• Stop 3% hypertonic saline when severe symptoms resolve and switch to mild symptoms protocol 1

For Cerebral Salt Wasting (CSW)

• Volume repletion with normal saline is the primary approach 2
• For severe symptoms, administer 3% hypertonic saline and consider fludrocortisone 2
• Avoid fluid restriction as it can worsen outcomes 1, 2

Special Considerations

• Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require more cautious correction (4-6 mmol/L per day) 2
• Chronic hyponatremia should not be rapidly corrected (>1 mmol/L/h) 1, 5
• If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 2
• Tolvaptan should only be initiated in a hospital setting with close monitoring of serum sodium 6

Pharmacological Options

• 3% hypertonic saline: First-line for severe symptomatic hyponatremia 1, 2, 3
• Vasopressin receptor antagonists (tolvaptan): Consider for euvolemic or hypervolemic hyponatremia resistant to conventional therapy 6, 4
  • Starting dose: 15 mg once daily, may increase to 30 mg after 24 hours if needed 6
  • Must be initiated in hospital with frequent monitoring 6
• Urea: Effective second-line therapy for SIADH 4
• Fludrocortisone: Consider for CSW, especially in subarachnoid hemorrhage patients 2

Monitoring and Follow-up

• For severe symptoms: Monitor serum sodium every 2 hours during initial correction 1, 2
• For mild symptoms: Monitor serum sodium every 4 hours initially, then daily 1
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 2

Common Pitfalls to Avoid

• Overly rapid correction exceeding 8 mmol/L in 24 hours can lead to osmotic demyelination syndrome 1, 2, 7
• Using fluid restriction in CSW can worsen outcomes 1, 2
• Inadequate monitoring during active correction 2
• Failing to recognize and treat the underlying cause 2
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 2