Symptomatic Hyponatremia Treatment
For severe symptomatic hyponatremia (seizures, altered mental status, coma), immediately administer 3% hypertonic saline with a target correction of 6 mmol/L over 6 hours or until symptoms resolve, never exceeding 8 mmol/L total correction in 24 hours. 1
Immediate Management for Severe Symptoms
Severe symptoms requiring emergency treatment include:
- Seizures, coma, or altered consciousness 1
- Confusion, delirium, or somnolence 2, 3
- Respiratory distress 2
Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, repeatable up to three times at 10-minute intervals until symptoms improve. 1 This approach provides rapid correction while maintaining control over the rate of sodium increase. 4
Critical correction limits:
- Target 6 mmol/L increase over first 6 hours OR until severe symptoms resolve 1
- Maximum 8 mmol/L correction in 24 hours 1, 5
- Never exceed 10-12 mmol/L in 24 hours under any circumstances 1, 3
Monitoring During Acute Treatment
Check serum sodium every 2 hours during initial correction for severe symptoms. 1 Once severe symptoms resolve, transition to every 4-hour monitoring. 1
Watch diuresis closely—it correlates directly with overcorrection risk. 4 If urine output increases dramatically, reduce bolus volume and reassess before repeating infusions. 4
Treatment Based on Symptom Severity
Moderate Symptoms (Nausea, Headache, Weakness)
For moderate symptoms without life-threatening features, use more conservative correction:
- 3% hypertonic saline may still be appropriate but with slower infusion rates 1
- Target 4-6 mmol/L increase over 24 hours 1
- Overcorrection occurs less frequently (6%) compared to severe symptoms (38%) 4
Mild or Asymptomatic
Fluid restriction to 1 L/day is first-line for euvolemic hyponatremia (SIADH). 1 Add oral sodium chloride 100 mEq three times daily if fluid restriction fails. 6
High-Risk Populations Requiring Slower Correction
Patients with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy require maximum correction of only 4-6 mmol/L per day. 1, 5 These populations have dramatically increased risk of osmotic demyelination syndrome, even with standard correction rates. 1
Critical Safety Considerations
Osmotic demyelination syndrome results from overly rapid correction (>8-12 mmol/L in 24 hours) and manifests as dysarthria, dysphagia, quadriparesis, seizures, or death, typically 2-7 days after correction. 1, 5, 3 This complication is irreversible and potentially fatal. 7
If overcorrection occurs, immediately discontinue hypertonic saline, switch to D5W (5% dextrose in water), and consider desmopressin to relower sodium levels. 1
Common Pitfalls to Avoid
Never use fluid restriction as initial treatment for severely symptomatic hyponatremia—this is a medical emergency requiring hypertonic saline. 1 Fluid restriction is appropriate only for mild/asymptomatic euvolemic hyponatremia. 1
Never correct chronic hyponatremia (>48 hours duration) faster than 8 mmol/L in 24 hours. 1, 3 Acute hyponatremia (<48 hours) can tolerate more rapid correction, but chronic cases cannot. 1
Inadequate monitoring during active correction is a critical error. 1 Serum sodium must be checked every 2 hours initially for severe symptoms. 1
Post-Acute Management
Once severe symptoms resolve and sodium reaches 125-130 mmol/L, transition to etiology-specific treatment:
- SIADH (euvolemic): Fluid restriction 1 L/day, add oral sodium chloride 100 mEq three times daily if needed 1, 6
- Hypovolemic: Continue isotonic saline for volume repletion 1
- Hypervolemic (heart failure, cirrhosis): Fluid restriction 1-1.5 L/day, avoid hypertonic saline unless life-threatening 1
- Cerebral salt wasting: Volume and sodium replacement with normal saline or hypertonic saline plus fludrocortisone 1
Following discontinuation of hypertonic saline, resume previous therapies and monitor sodium levels for 7 days. 5 Patients should be advised to resume fluid restriction and continue close monitoring. 5