How do you correct severe symptomatic hyponatremia?

Management of Severe Symptomatic Hyponatremia

For severe symptomatic hyponatremia, administer 3% hypertonic saline with an initial goal to correct sodium by 6 mmol/L over 6 hours or until severe symptoms resolve, with a maximum correction of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome. 1, 2

Initial Assessment and Treatment

• Determine symptom severity - severe symptoms include seizures, coma, and respiratory distress requiring immediate intervention with 3% hypertonic saline 1, 3
• For severe symptomatic hyponatremia, administer 3% hypertonic saline as boluses of 100 mL over 10 minutes, which can be repeated up to three times at 10-minute intervals until symptoms improve 1, 4
• Calculate sodium deficit using formula: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1, 3
• Monitor serum sodium every 2 hours during initial correction 1

Correction Rate Guidelines

• Initial goal: Correct sodium by 6 mmol/L over 6 hours or until severe symptoms resolve 1, 2, 3
• Maximum correction: 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 2, 3
• After initial 6 mmol/L correction, limit to only 2 mmol/L in the following 18 hours 2
• For patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy, use more cautious correction (4-6 mmol/L per day) due to higher risk of osmotic demyelination 1

Transition After Symptom Resolution

• Discontinue 3% normal saline when severe symptoms resolve 2
• Switch to protocols for mild symptoms or asymptomatic hyponatremia 2
• Continue monitoring serum sodium levels every 4 hours instead of every 2 hours 2
• Implement fluid restriction to 1L/day 1, 2, 3
• For mild symptoms or asymptomatic patients, add oral sodium chloride 100 mEq three times daily if needed 3

Management Based on Underlying Cause

• For SIADH: Fluid restriction to 1 L/day is the cornerstone of treatment, with addition of oral sodium chloride if needed 1, 3
• For Cerebral Salt Wasting (CSW): Volume repletion with normal saline is the primary approach, with 3% hypertonic saline and fludrocortisone for severe symptoms 1, 3
• For hypovolemic hyponatremia: Discontinue diuretics and administer isotonic saline for volume repletion 1
• For hypervolemic hyponatremia (cirrhosis, heart failure): Fluid restriction to 1-1.5 L/day and consider albumin infusion 1, 3

Prevention of Complications

• If overcorrection occurs, consider relowering with electrolyte-free water or desmopressin 1, 5
• Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction 1
• Avoid fluid restriction in patients with cerebral salt wasting, as this can worsen outcomes 1

Special Considerations

• For chronic hyponatremia (>48-72 hours), slower correction is safer after initial symptom control 2, 6
• Vasopressin receptor antagonists (tolvaptan) should not be used for urgent correction of severe symptomatic hyponatremia 7
• Consider ICU admission for close monitoring during treatment of severe symptomatic hyponatremia 1, 8
• Recent evidence suggests that rapid intermittent bolus and slow continuous infusion of 3% hypertonic saline are both safe and effective for managing severe symptomatic hyponatremia 4

Common Pitfalls to Avoid

• Overly rapid correction exceeding 8 mmol/L in 24 hours can lead to osmotic demyelination syndrome 1, 2, 9
• Inadequate monitoring during active correction 1
• Using fluid restriction in CSW can worsen outcomes 1
• Failing to recognize and treat the underlying cause 1
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1