How to correct hyponatremia (low sodium levels)?

From the Guidelines

Correcting hyponatremia requires a careful approach to manage sodium levels and address the underlying cause, with the goal of improving morbidity, mortality, and quality of life.

Approach to Correction

For mild to moderate hyponatremia (sodium 125-135 mEq/L) with minimal symptoms, fluid restriction to 800-1000 mL/day is often the first approach, particularly in cases of dilutional hyponatremia 1.

• Key considerations include:
  • Identifying and addressing the underlying cause of hyponatremia
  • Carefully managing sodium levels to avoid too rapid correction
  • Monitoring for signs of osmotic demyelination syndrome

Severe or Symptomatic Hyponatremia

For more severe or symptomatic cases (sodium <125 mEq/L with neurological symptoms), hypertonic saline (3% NaCl) may be administered intravenously, typically at 1-2 mL/kg/hour, with close monitoring to avoid correcting sodium levels too rapidly 1.

• The correction rate should generally not exceed 8-10 mEq/L in 24 hours to prevent osmotic demyelination syndrome
• Specific medications like tolvaptan (starting at 15 mg daily) or conivaptan may be used for SIADH-related hyponatremia 1

Monitoring and Adjustments

Regular monitoring of serum sodium levels (every 2-4 hours initially in severe cases) is essential during correction 1.

• Patients should understand that too-rapid correction can cause serious neurological complications, while insufficient correction may not resolve symptoms like confusion, seizures, or altered mental status that can occur with significant hyponatremia
• Underlying causes such as medication effects, hormonal imbalances, or excessive fluid intake must be addressed simultaneously 1

From the FDA Drug Label

Tolvaptan tablets should be initiated and re-initiated in patients only in a hospital where serum sodium can be monitored closely. Too rapid correction of hyponatremia (e.g., > 12 mEq/L/24 hours) can cause osmotic demyelination resulting in dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma and death. In susceptible patients, including those with severe malnutrition, alcoholism or advanced liver disease, slower rates of correction may be advisable The usual starting dose for tolvaptan tablets is 15 mg administered once daily without regard to meals. Increase the dose to 30 mg once daily, after at least 24 hours, to a maximum of 60 mg once daily, as needed to achieve the desired level of serum sodium.

To correct hyponatremia, initiate and re-initiate tolvaptan in a hospital where serum sodium can be closely monitored. The recommended starting dose is 15 mg once daily, and the dose can be increased to 30 mg once daily after at least 24 hours, up to a maximum of 60 mg once daily. It is crucial to avoid too rapid correction of serum sodium (greater than 12 mEq/L/24 hours) to prevent serious neurologic sequelae, such as osmotic demyelination syndrome. In susceptible patients, including those with severe malnutrition, alcoholism, or advanced liver disease, slower rates of correction may be advisable 2.

From the Research

Correction of Hyponatremia

To correct hyponatremia, the following steps can be taken:

• Identify the underlying cause of hyponatremia, such as syndrome of inappropriate antidiuretic hormone (SIADH) secretion, heart failure, or liver cirrhosis 3, 4, 5
• Categorize patients according to their fluid volume status: hypovolemic, euvolemic, or hypervolemic 3, 4, 6, 5
• Treat symptomatic hyponatremia promptly with 3% hypertonic saline to increase serum sodium by 1-2 mmol/L per hour until symptoms abate 3, 4, 7, 6
• For asymptomatic patients with chronic hyponatremia, fluid restriction and close monitoring alone may be sufficient 4, 6

Treatment Approaches

Different treatment approaches can be used depending on the underlying cause and volume status:

• Hypovolemic hyponatremia: treat with normal saline infusions 7, 6, 5
• Euvolemic hyponatremia: restrict free water consumption, use salt tablets or intravenous vaptans 3, 4, 7, 5
• Hypervolemic hyponatremia: manage underlying cause (e.g. heart failure, cirrhosis) and restrict free water intake 3, 4, 7, 6, 5
• Vasopressin receptor antagonists can provide prompt and effective water diuresis and increase in serum sodium concentration in both euvolemic and hypervolemic hyponatremia 3

Important Considerations

• Avoid overly rapid correction of hyponatremia (>12 mmol/L per 24 hours) to prevent serious neurologic injury, such as osmotic demyelination syndrome 3, 4, 7, 6
• Use calculators to guide fluid replacement and avoid excessive rapid correction 7
• Identify and treat the underlying cause of hyponatremia to prevent recurrence 3, 4, 5