How to correct hyponatremia?

Management of Hyponatremia

The treatment of hyponatremia must be based on the underlying cause, volume status, and symptom severity, with careful attention to correction rates to prevent osmotic demyelination syndrome. 1

Initial Assessment

• Determine the underlying cause by assessing volume status (hypovolemic, euvolemic, or hypervolemic), serum and urine osmolality, urine electrolytes, and uric acid levels 1
• Classify hyponatremia severity: mild (130-134 mmol/L), moderate (125-129 mmol/L), or severe (<125 mmol/L) 2
• Evaluate for symptoms: mild (nausea, headache, weakness) vs. severe (seizures, coma, altered mental status) 1

Treatment Based on Volume Status

Hypovolemic Hyponatremia

• Discontinue diuretics if they are the cause 3, 1
• Administer isotonic saline (0.9% NaCl) for volume repletion 1, 2
• Once volume is restored, monitor for spontaneous correction of serum sodium 1
• For severe dehydration with neurological symptoms, consider hypertonic saline with careful monitoring 3

Euvolemic Hyponatremia (e.g., SIADH)

• Implement fluid restriction (1-1.5 L/day) for moderate cases (Na 120-125 mmol/L) 3, 1
• For severe symptomatic cases, administer 3% hypertonic saline with close monitoring 1, 4
• Consider oral sodium chloride supplementation if fluid restriction alone is insufficient 1
• For refractory cases, tolvaptan may be considered (starting dose 15 mg once daily) but must be initiated in hospital setting 5

Hypervolemic Hyponatremia (e.g., cirrhosis, heart failure)

• Implement fluid restriction to 1-1.5 L/day for serum sodium <125 mmol/L 3, 1
• Address the underlying cause (e.g., heart failure, cirrhosis management) 2
• Consider albumin infusion for patients with cirrhosis 3
• Avoid hypertonic saline unless life-threatening symptoms are present, as it may worsen edema and ascites 3

Correction Rate Guidelines

• For severe symptomatic hyponatremia: Correct by 4-6 mmol/L in the first 6 hours or until symptoms improve 1, 6
• Maximum correction rate: Do not exceed 8 mmol/L in 24 hours to prevent osmotic demyelination syndrome 1, 5
• For patients with liver disease or malnutrition: Use even more conservative correction rates (4-6 mmol/L per day) due to higher risk of osmotic demyelination 1, 3
• Monitor serum sodium frequently: Every 2-4 hours during active correction 1

Special Considerations

Vaptans (Vasopressin Receptor Antagonists)

• Tolvaptan is FDA-approved for clinically significant hypervolemic and euvolemic hyponatremia 5
• Must be initiated in a hospital setting with close monitoring of serum sodium 5
• Starting dose is 15 mg once daily, which can be increased to 30 mg after 24 hours if needed 5
• Do not administer for more than 30 days due to risk of liver injury 5
• Avoid fluid restriction during the first 24 hours of tolvaptan therapy 5
• Contraindicated in hypovolemic hyponatremia and in patients unable to sense or respond to thirst 5

Cerebral Salt Wasting (CSW)

• Unlike SIADH, CSW requires volume and sodium replacement rather than fluid restriction 1
• Treatment focuses on isotonic or hypertonic saline and may include fludrocortisone 1

Common Pitfalls to Avoid

• Overly rapid correction (>8 mmol/L/24 hours) leading to osmotic demyelination syndrome 1, 5
• Using fluid restriction in CSW, which can worsen outcomes 1
• Inadequate monitoring during active correction 1
• Using hypertonic saline in hypervolemic hyponatremia without life-threatening symptoms 1
• Failing to recognize and treat the underlying cause 1
• Administering hypotonic fluids to patients with SIADH, which can worsen hyponatremia 1

Practical Approach to Severe Symptomatic Hyponatremia

1. Administer 3% hypertonic saline (100 mL bolus over 10-15 minutes) 4, 6
2. Monitor serum sodium every 1-2 hours until symptoms improve 1
3. Aim for 4-6 mmol/L increase in the first 6 hours or until severe symptoms resolve 1
4. Once symptoms improve, slow the correction rate to stay within the 8 mmol/L per 24-hour limit 1, 5
5. Calculate sodium deficit to guide therapy: Desired increase in Na (mEq/L) × (0.5 × ideal body weight in kg) 1

By following these guidelines and carefully monitoring correction rates, hyponatremia can be safely and effectively managed while minimizing the risk of complications.