What is the goal of correcting hyponatremia?

Goal of Correction of Hyponatremia

The goal of correcting hyponatremia is to increase serum sodium by 4-6 mEq/L in 24 hours, not exceeding 8 mEq/L in 24 hours, to avoid osmotic demyelination syndrome while effectively treating symptoms. 1

Correction Rate Guidelines

Standard Correction Targets

• For most patients: 4-6 mEq/L in 24 hours 1
• Maximum safe correction: 8 mEq/L in 24 hours 1, 2
• For severe symptomatic hyponatremia: 4-6 mEq/L in first 1-2 hours using 3% hypertonic saline boluses 1

Special Considerations

• High-risk patients (severe malnutrition, alcoholism, advanced liver disease): Consider slower correction rates 2
• Advanced kidney disease patients: Require closer monitoring due to increased risk of osmotic demyelination syndrome 1

Monitoring During Correction

• Frequency: Monitor serum sodium every 4-6 hours during active correction 1
• Neurological assessment: Regular evaluation for signs of either worsening hyponatremia or osmotic demyelination syndrome 1
• Warning signs for overcorrection: If correction exceeds targets, treatment should be suspended 1
• Critical threshold: Suspend infusion if serum sodium exceeds 155 mEq/L 1

Risks of Inappropriate Correction

Too Slow Correction

• Recent evidence suggests that very slow correction (<4-6 mEq/L per 24 hours) is associated with increased mortality compared to more rapid correction 3
• May lead to persistent neurological symptoms and increased hospital length of stay 3

Too Rapid Correction

• Correction >12 mEq/L/24 hours can cause osmotic demyelination syndrome 2
• Symptoms include dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma, and death 2
• Osmotic demyelination typically presents 2-7 days after rapid correction 1

Treatment Strategies Based on Volume Status

Hypervolemic Hyponatremia

• Fluid restriction to 1,000-1,500 mL/day 1
• Consider albumin infusion for severe hyponatremia (<120 mEq/L) 1
• Diuretic therapy with spironolactone (starting at 100 mg, up to 400 mg) 1

Euvolemic Hyponatremia (SIADH)

• Fluid restriction, urea, or tolvaptan depending on severity and response 1
• Tolvaptan starting dose: 15 mg once daily, maximum 60 mg daily (not to exceed 30 days due to liver injury risk) 1, 2
• Alternative: Midodrine (7.5 mg three times daily) when vaptans unavailable 1

Hypovolemic Hyponatremia

• Normal saline infusion is recommended 1

Prevention of Complications

• Avoid fluid restriction during first 24 hours of tolvaptan therapy 2
• Hospital initiation of tolvaptan and other therapies that may rapidly correct sodium 2
• If overcorrection occurs, consider therapeutic relowering of serum sodium 4
• For patients at risk of water diuresis causing overcorrection, consider concurrent desmopressin administration with hypertonic saline 5
• Elevate head of bed to 30-degree angle if cerebral edema is present 1

Key Pitfalls to Avoid

1. Inadvertent overcorrection is common and dangerous - have a clear correction plan and monitor frequently
2. Failure to recognize high-risk patients who need slower correction rates
3. Overly conservative correction may increase mortality in severely symptomatic patients
4. Not adjusting therapy when correction is occurring too rapidly or too slowly
5. Using tolvaptan for ADPKD - this is contraindicated due to hepatotoxicity risk 2

Remember that the goal of treatment is to safely correct sodium levels while preventing both the neurological complications of hyponatremia and the iatrogenic complications of treatment.