What is the treatment for symptomatic hyponatremia?

Treatment of Symptomatic Hyponatremia

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 in 24 hours to prevent osmotic demyelination syndrome. 1

Immediate Management for Severe Symptoms

Administer 3% hypertonic saline as 100 mL boluses over 10 minutes, which can be repeated up to 3 times at 10-minute intervals until neurological symptoms improve. 1, 2 This approach rapidly reverses hyponatremic encephalopathy while maintaining control over correction rates. 1

Critical Correction Limits

• Maximum correction: 8 mmol/L in 24 hours for most patients 1, 2
• High-risk patients (cirrhosis, alcoholism, malnutrition, advanced liver disease): 4-6 mmol/L per day maximum 1, 2
• Initial target: 6 mmol/L increase over first 6 hours or until severe symptoms resolve 1, 2
• Never exceed 12 mmol/L in 24 hours under any circumstances 3, 4

The FDA explicitly warns that correction rates exceeding 12 mmol/L per 24 hours can cause osmotic demyelination resulting in dysarthria, mutism, dysphagia, lethargy, spastic quadriparesis, seizures, coma and death. 3

Monitoring Protocol

Check serum sodium every 2 hours during initial correction for severe symptoms. 1, 2 Once symptoms resolve, transition to every 4-6 hours monitoring. 1 This intensive monitoring is mandatory to prevent overcorrection, which occurs in 4.5-28% of cases even with careful management. 5

Treatment Based on Symptom Severity

Severe Symptoms (Medical Emergency)

• Confusion, seizures, coma, altered consciousness, respiratory distress 6
• Treatment: 3% hypertonic saline boluses immediately 1, 4
• Goal: Increase sodium by 1-2 mmol/L per hour until symptoms abate 4
• ICU admission required for close monitoring 1

Mild-Moderate Symptoms

• Nausea, vomiting, headache, muscle cramps, lethargy, gait instability 6
• Treatment approach depends on volume status and chronicity 1
• Fluid restriction to 1 L/day for SIADH 1
• Add oral sodium chloride 100 mEq three times daily if no response to fluid restriction 1

Management by Volume Status

Hypovolemic Hyponatremia

Discontinue diuretics and administer isotonic saline (0.9% NaCl) for volume repletion. 1 Urine sodium <30 mmol/L predicts 71-100% response to saline infusion. 1 Correct volume depletion first, then reassess sodium levels. 1

Euvolemic Hyponatremia (SIADH)

Fluid restriction to 1 L/day is the cornerstone of treatment. 1, 4 For severe symptoms, use 3% hypertonic saline. 1 If fluid restriction fails after 24-48 hours, add oral sodium chloride supplementation or consider vaptans. 1, 3

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

Implement fluid restriction to 1-1.5 L/day for sodium <125 mmol/L. 1 Temporarily discontinue diuretics. 1 Consider albumin infusion in cirrhotic patients. 1 Avoid hypertonic saline unless life-threatening symptoms are present, as it worsens fluid overload. 1

Special Populations Requiring Slower Correction

Patients with advanced liver disease, alcoholism, severe malnutrition, or prior encephalopathy require maximum correction of only 4-6 mmol/L per day. 1, 2, 3 These populations have completed brain adaptation and face substantially higher risk of osmotic demyelination syndrome. 1

Management of Overcorrection

If sodium correction exceeds 8 mmol/L in 24 hours, immediately discontinue all sodium-containing fluids and switch to D5W (5% dextrose in water). 1, 2 Consider administering desmopressin to terminate water diuresis and relower sodium levels. 1, 7 The goal is to bring total 24-hour correction back below 8 mmol/L from the starting point. 1

Acute vs. Chronic Hyponatremia

**Acute hyponatremia (<48 hours) can be corrected more rapidly without risk of osmotic demyelination, as brain adaptation has not occurred.** 1, 8, 7 Chronic hyponatremia (>48 hours) requires strict adherence to the 8 mmol/L per 24-hour limit due to completed brain adaptation. 1, 8, 7

Pharmacological Options for Refractory Cases

Tolvaptan (vasopressin receptor antagonist) may be considered for euvolemic or hypervolemic hyponatremia resistant to fluid restriction, starting at 15 mg once daily. 3 However, the FDA mandates hospital initiation with close sodium monitoring due to risk of overly rapid correction. 3 Tolvaptan should not be used for more than 30 days due to hepatotoxicity risk. 3

Critical Pitfalls to Avoid

• Never use fluid restriction as initial treatment for severe symptomatic hyponatremia—this is a medical emergency requiring hypertonic saline 1
• Never exceed 8 mmol/L correction in 24 hours for chronic hyponatremia 1, 2, 3
• Never use hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1
• Never use fluid restriction in cerebral salt wasting—this worsens outcomes 1
• Inadequate monitoring during active correction leads to overcorrection and osmotic demyelination 1

Post-Treatment Considerations

Following discontinuation of treatment, resume fluid restriction and monitor for sodium rebound. 3 Watch for signs of osmotic demyelination syndrome (dysarthria, dysphagia, oculomotor dysfunction, quadriparesis) typically occurring 2-7 days after rapid correction. 1 Even mild chronic hyponatremia (130-135 mmol/L) should not be ignored, as it increases fall risk 21% vs 5% and carries a 60-fold increase in hospital mortality. 1, 6, 5