Hyponatremia Correction

Correction Rate Guidelines

The maximum correction rate should not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome, with high-risk patients requiring even slower correction at 4-6 mmol/L per day. 1

Standard Correction Limits

Maximum correction: 8 mmol/L per 24 hours for most patients 1, 2
High-risk patients: 4-6 mmol/L per day (those with advanced liver disease, alcoholism, malnutrition, or prior encephalopathy) 1
The FDA warns that correction >12 mEq/L/24 hours can cause osmotic demyelination resulting in dysarthria, mutism, dysphagia, lethargy, seizures, coma, and death 2

Acute vs. Chronic Hyponatremia

Acute hyponatremia (<48 hours): Can be corrected more rapidly without risk of osmotic demyelination 1, 3
Chronic hyponatremia (>48 hours): Requires slower, more cautious correction due to brain adaptation mechanisms 1, 4

Treatment Based on Symptom Severity

Severe Symptomatic Hyponatremia (Seizures, Coma, Altered Mental Status)

Administer 3% hypertonic saline immediately with a target correction of 6 mmol/L over 6 hours or until severe symptoms resolve. 1

Initial bolus: 100 mL of 3% saline over 10 minutes, can repeat up to 3 times at 10-minute intervals 1
Goal: Increase sodium by 4-6 mEq/L within 1-2 hours to reverse hyponatremic encephalopathy 5
After initial 6 mmol/L correction: Limit to only 2 mmol/L additional correction in the following 18 hours 1
Monitoring: Check serum sodium every 2 hours during initial correction 1
ICU admission: Required for close monitoring 1

Mild to Moderate Symptoms or Asymptomatic

Treatment should focus on addressing the underlying cause and volume status, with fluid restriction as the cornerstone for euvolemic hyponatremia (SIADH). 1

Fluid restriction: 1 L/day for SIADH 1
Oral sodium supplementation: Add sodium chloride 100 mEq three times daily if no response to fluid restriction 1
Monitoring: Check serum sodium every 4 hours initially, then daily 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

Discontinue diuretics and administer isotonic saline (0.9% NaCl) for volume repletion. 1

Diagnostic clue: Urine sodium <30 mmol/L has 71-100% positive predictive value for response to saline 1
Avoid: Hypotonic fluids, which can worsen hyponatremia 1
Once euvolemic: Continue isotonic fluids until volume status normalized 1

Euvolemic Hyponatremia (SIADH)

Fluid restriction to 1 L/day is the primary treatment. 1

First-line: Fluid restriction <1 L/day 1, 5
Second-line pharmacological options:
- Oral sodium chloride 100 mEq three times daily 1
- Urea (effective but poor palatability) 5
- Demeclocycline or lithium (less commonly used due to side effects) 1
Tolvaptan: Starting dose 15 mg once daily, can titrate to 30-60 mg daily 2
- Must be initiated in hospital with close sodium monitoring 2
- Limit use to 30 days to minimize liver injury risk 2

Hypervolemic Hyponatremia (Heart Failure, Cirrhosis)

Implement fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L. 1

Fluid restriction: 1-1.5 L/day 1
Discontinue diuretics temporarily if sodium <125 mmol/L 1
Cirrhotic patients: Consider albumin infusion alongside fluid restriction 1
Avoid hypertonic saline unless life-threatening symptoms present, as it worsens ascites and edema 1
Sodium restriction (not fluid restriction) results in weight loss, as fluid follows sodium 1

Special Populations

Neurosurgical Patients

Distinguish between SIADH and cerebral salt wasting (CSW), as treatment approaches differ fundamentally. 1

CSW treatment: Volume and sodium replacement with isotonic or hypertonic saline, NOT fluid restriction 1
Severe CSW: 3% hypertonic saline plus fludrocortisone in ICU 1
Subarachnoid hemorrhage patients: Avoid fluid restriction in those at risk for vasospasm 1
Fludrocortisone: May be considered to prevent vasospasm 1
Hydrocortisone: May prevent natriuresis 1

Cirrhotic Patients

Use conservative correction rates of 4-6 mmol/L per day due to higher risk of osmotic demyelination syndrome. 1

Maximum correction: 4-6 mmol/L per day, not exceeding 8 mmol/L in 24 hours 1
Tolvaptan caution: Higher risk of gastrointestinal bleeding (10% vs 2% placebo) 1
Clinical significance: Hyponatremia increases risk of spontaneous bacterial peritonitis (OR 3.40), hepatorenal syndrome (OR 3.45), and hepatic encephalopathy (OR 2.36) 1

Monitoring and Prevention of Complications

Monitoring Protocol

Severe symptoms: Every 2 hours during initial correction 1
After symptom resolution: Every 4 hours 1
Mild symptoms or asymptomatic: Every 4 hours initially, then daily 1

Osmotic Demyelination Syndrome Prevention

Osmotic demyelination syndrome occurs when correction exceeds 8 mmol/L in 24 hours, typically presenting 2-7 days after rapid correction. 1

Signs to monitor: Dysarthria, dysphagia, oculomotor dysfunction, quadriparesis 1, 2
High-risk factors: Severe malnutrition, alcoholism, advanced liver disease, hypokalemia 1, 2

Management of Overcorrection

If overcorrection occurs (>8 mmol/L in 24 hours), immediately discontinue current fluids and switch to D5W. 1

Immediate action: Stop current fluids, switch to D5W (5% dextrose in water) 1
Consider desmopressin: To slow or reverse rapid sodium rise 1
Goal: Bring total 24-hour correction to no more than 8 mEq/L from starting point 1

Common Pitfalls to Avoid

Ignoring mild hyponatremia (130-135 mmol/L): Even mild chronic hyponatremia increases fall risk (21% vs 5%) and mortality (60-fold increase) 1, 6
Using fluid restriction in CSW: Worsens outcomes; CSW requires volume replacement 1
Inadequate monitoring during active correction: Can lead to overcorrection and osmotic demyelination 1
Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms: Worsens edema and ascites 1
Failing to recognize and treat underlying cause: Essential for long-term management 1
Overly rapid correction in chronic hyponatremia: Most common cause of osmotic demyelination syndrome 1

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