Treatment of Severe Hyponatremia with 3% Hypertonic Saline
For severe symptomatic hyponatremia, administer up to three 100 mL boluses of 3% hypertonic saline spaced at 10-minute intervals to correct symptoms. 1
Dosing Recommendations Based on Symptom Severity
Severe Symptomatic Hyponatremia (Confusion, Seizures, Coma)
- Initial treatment: Up to three 100 mL boluses of 3% hypertonic saline given at 10-minute intervals 1
- Target: Increase serum sodium by 1-2 mmol/L per hour until symptoms abate 2
- Maximum correction: 12 mmol/L in 24 hours or 18 mmol/L in 48 hours 2
Monitoring During Treatment
- Check serum sodium every 2-4 hours initially, then every 4-6 hours once stabilized 3
- Monitor vital signs every 1-2 hours initially 3
- Perform daily renal function tests and electrolytes with each sodium check 3
Evidence-Based Approach to Administration
Recent evidence supports bolus administration over continuous infusion:
- Bolus therapy produces faster initial elevation of serum sodium than continuous infusion (6 mmol/L vs 3 mmol/L at 6 hours) 4
- Faster improvement in Glasgow Coma Scale with bolus therapy 4
- More consistent sodium correction with hypertonic saline boluses compared to conventional therapies 5
Important Considerations and Pitfalls
Preventing Overcorrection
- Risk of overcorrection is higher in patients with severe symptoms (38% vs 6% in moderate symptoms) 5
- After administering the third saline bolus, there is a significantly greater need for dextrose/dDAVP to prevent overcorrection (OR 24) 4
- Monitor diuresis closely as it correlates positively with the degree of sodium overcorrection 5
Avoiding Osmotic Demyelination Syndrome
- Never exceed correction rate of 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 3, 6
- Patients with alcoholism, malnutrition, or liver disease are at higher risk for osmotic demyelination and require more cautious correction 3
Calculating Initial Infusion Rate
- Initial infusion rate (ml/kg per hour) can be estimated by: body weight (kg) × desired rate of increase in sodium (mmol/L per hour) 2
- For most patients, this translates to the recommended 100 mL boluses
Alternative Approaches for Specific Situations
For mild to moderate symptomatic hyponatremia:
- Consider oral hypertonic solutions if the patient can tolerate oral intake 1
- In one study, 16 runners with exercise-associated hyponatremia recovered within 30 minutes after drinking concentrated oral hypertonic solution 1
For asymptomatic hyponatremia:
- Adequate solute intake with initial fluid restriction of 500 ml/day adjusted according to serum sodium levels 6
The bolus approach to 3% saline administration is now preferred over continuous infusion for symptomatic hyponatremia due to faster correction of sodium levels and quicker improvement in neurological symptoms 6, 4.