How do you treat hyponatremia?

From the Guidelines

Treatment of hyponatremia should be guided by its severity, onset speed, and underlying cause, with the goal of correcting serum sodium levels without exceeding 8 mEq/L per 24-hour period to prevent osmotic demyelination syndrome, as recommended by the most recent guidelines 1.

Approach to Treatment

The approach to treating hyponatremia involves:

• For mild to moderate cases (sodium >120 mEq/L) with minimal symptoms, fluid restriction to 800-1000 mL/day is often the first approach.
• For more severe or symptomatic hyponatremia, 3% hypertonic saline may be administered intravenously at 1-2 mL/kg/hour, with careful monitoring to avoid correcting sodium levels too quickly.
• Vasopressin receptor antagonists, such as tolvaptan, can be used for short-term treatment (≤30 days) in cirrhosis, but with caution and close monitoring of serum sodium levels.

Key Considerations

• Addressing the underlying cause is crucial, including discontinuing offending medications, treating infections, or managing heart failure, liver disease, or adrenal insufficiency.
• Ongoing monitoring of serum sodium, fluid status, and neurological signs is essential during treatment to balance the risks of hyponatremia itself against the dangers of overly rapid correction.
• The goal rate of increase of serum sodium is 4-6 mEq/L per 24-hour period, not to exceed 8 mEq/L per 24-hour period, to ameliorate the risk of osmotic demyelination syndrome, as recommended by recent guidelines 1.

Specific Recommendations

• For severe hyponatremia (<120 mEq/L), water restriction and albumin infusion may be recommended, along with careful consideration of the use of hypertonic saline or vasopressin receptor antagonists.
• Multidisciplinary coordinated care may mitigate the risk of osmotic demyelination syndrome in patients with severe hyponatremia undergoing liver transplantation.

From the FDA Drug Label

In two double-blind, placebo-controlled, multi-center studies (SALT-1 and SALT-2), a total of 424 patients with euvolemic or hypervolemic hyponatremia (serum sodium <135 mEq/L) resulting from a variety of underlying causes (heart failure, liver cirrhosis, syndrome of inappropriate antidiuretic hormone [SIADH] and others) were treated for 30 days with tolvaptan or placebo, then followed for an additional 7 days after withdrawal. The primary endpoint for these studies was the average daily AUC for change in serum sodium from baseline to Day 4 and baseline to Day 30 in patients with a serum sodium less than 135 mEq/L. Compared to placebo, tolvaptan caused a statistically greater increase in serum sodium ( p <0. 0001) during both periods in both studies

Treatment of Hyponatremia: Tolvaptan can be used to treat hyponatremia. The initial oral dose is 15 mg once daily, and the dose can be increased at 24-hour intervals to 30 mg once daily, then to 60 mg once daily, until either the maximum dose of 60 mg or normonatremia (serum sodium >135 mEq/L) is reached.

• Key Points:
  • Tolvaptan is effective in increasing serum sodium levels in patients with euvolemic or hypervolemic hyponatremia.
  • The treatment should be maintained for 30 days.
  • Fluid restriction should be avoided if possible during the first 24 hours of therapy to avoid overly rapid correction of serum sodium.
  • Patients can resume or initiate fluid restriction as clinically indicated after the first 24 hours of therapy 2

From the Research

Treatment of Hyponatremia

The treatment of hyponatremia depends on the underlying cause, severity of symptoms, and volume status of the patient 3, 4, 5, 6, 7.

• Hypovolemic hyponatremia is treated with normal saline infusions to correct the fluid deficit.
• Euvolemic hyponatremia is treated by restricting free water consumption or using salt tablets or intravenous vaptans.
• Hypervolemic hyponatremia is treated primarily by managing the underlying cause (e.g., heart failure, cirrhosis) and free water restriction.

Severe Symptomatic Hyponatremia

Severely symptomatic hyponatremia (with signs of somnolence, obtundation, coma, seizures, or cardiorespiratory distress) is a medical emergency that requires immediate treatment with bolus hypertonic saline to reverse hyponatremic encephalopathy 3, 4, 6.

• The goal is to increase the serum sodium level by 4 mEq/L to 6 mEq/L within 1 to 2 hours but by no more than 10 mEq/L within the first 24 hours.

Risks of Treatment

Overly rapid correction of chronic hyponatremia may cause osmotic demyelination, a rare but severe neurological condition, which can result in parkinsonism, quadriparesis, or even death 3, 5, 6.

• Therefore, it is essential to monitor the patient's clinical status and relevant serum biochemical values closely during treatment.

Management Approach

The approach to managing hyponatremia should consist of treating the underlying cause, and most patients should be managed according to their fluid volume status (hypovolemic, euvolemic, or hypervolemic) 3, 4, 7.

• Urea and vaptans can be effective treatments for the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure, but have adverse effects.