What is the recommended dose of 3% (three percent) saline solution for treating severe hyponatremia?

Dosing of 3% Saline Solution for Severe Hyponatremia

For severe hyponatremia (<120 mEq/L), 3% hypertonic saline should be administered to increase serum sodium by 4-6 mEq/L per 24-hour period, not exceeding 8 mEq/L per 24-hour period to reduce the risk of osmotic demyelination syndrome (ODS). 1

Patient Assessment and Risk Stratification

Before administering 3% saline, assess:

• Severity of symptoms (seizures, encephalopathy, coma)
• Duration of hyponatremia (acute vs. chronic)
• Risk factors for ODS:
  • Advanced liver disease
  • Alcoholism
  • Severe hyponatremia
  • Malnutrition
  • Metabolic derangements (hypophosphatemia, hypokalemia)
  • Low cholesterol
  • Prior encephalopathy 1

Dosing Protocol

For Symptomatic Severe Hyponatremia

• Initial bolus: Administer 3% saline to increase serum sodium by 1-2 mEq/L per hour until symptoms abate 2
• Target correction rate:
  • Standard risk: 4-8 mEq/L per day, not exceeding 10-12 mEq/L in 24 hours 1
  • High risk (liver disease): 4-6 mEq/L per day, not exceeding 8 mEq/L in 24 hours 1
  • Continue until serum sodium reaches 130 mEq/L 1

Practical Calculation

• Initial infusion rate (ml/kg per hour) = body weight (kg) × desired rate of increase in sodium (mEq/L per hour) 2
• For a 70 kg patient targeting 1 mEq/L per hour increase: 70 ml/hour of 3% saline

Monitoring Requirements

• Check serum sodium every 2-4 hours during active correction 3
• Monitor for signs of overcorrection:
  • Increased urine output
  • Rapid clinical improvement
  • Rising sodium levels exceeding target rates
• If overcorrection occurs, consider:
  • Stopping hypertonic saline
  • Administering electrolyte-free water
  • Using desmopressin to prevent further rises 1, 4

Special Considerations

Cirrhosis Patients

• Use hypertonic saline only for short-term treatment of symptomatic severe hyponatremia or pre-transplant patients 1
• Higher risk of ODS - use more conservative correction rates (4-6 mEq/L per day) 1
• Consider multidisciplinary coordination, especially if liver transplantation is imminent 1

Timing Considerations

• Reserve 3% saline for severely symptomatic acute hyponatremia or when transplant is imminent 1
• For chronic hyponatremia without severe symptoms, fluid restriction is preferred as first-line therapy 1

Pitfalls to Avoid

• Exceeding correction limits (>8 mEq/L in 24 hours in high-risk patients) can lead to ODS with devastating neurological consequences 3
• Failing to monitor sodium levels frequently during correction
• Not adjusting treatment based on patient response
• Using 3% saline in hypervolemic hyponatremia without addressing the underlying volume overload 1

By following these guidelines, you can safely administer 3% hypertonic saline to correct severe hyponatremia while minimizing the risk of osmotic demyelination syndrome, which can cause permanent neurological damage.