What is the treatment of hyponatremia (low sodium levels)?

From the Guidelines

The treatment of hyponatremia should be guided by its severity, onset speed, and underlying cause, with the goal of correcting serum sodium levels while minimizing the risk of osmotic demyelination syndrome, as recommended by the most recent guidelines 1. The approach to treating hyponatremia varies based on its classification into hypovolemic, euvolemic, or hypervolemic types.

• For hypovolemic hyponatremia, treatment involves addressing the underlying cause of volume depletion, such as discontinuing diuretics or providing fluid resuscitation with isotonic solutions like 0.9% normal saline 1.
• In cases of hypervolemic hyponatremia, as seen in cirrhosis or heart failure, management includes fluid restriction and, in some cases, the use of loop diuretics like furosemide, alongside consideration of vasopressin receptor antagonists for severe cases 1.
• For euvolemic hyponatremia, such as in the syndrome of inappropriate antidiuretic hormone secretion (SIADH), treatment may involve fluid restriction, oral urea, or vasopressin receptor antagonists like tolvaptan, with careful monitoring of serum sodium levels 1. The use of hypertonic saline is reserved for severe, symptomatic hyponatremia, with a goal of increasing serum sodium by 4-6 mEq/L in the first 24 hours, not exceeding 8-10 mEq/L in 24 hours to prevent osmotic demyelination syndrome, as per the latest guidance 1. Regular monitoring of serum sodium levels is crucial during treatment to ensure appropriate correction rates and to minimize the risk of complications such as osmotic demyelination syndrome. Addressing the underlying cause of hyponatremia, whether it be adjusting medications, treating infections, or managing endocrine disorders, is essential for long-term management. Given the potential for significant morbidity and mortality associated with both hyponatremia and its treatment, careful consideration of the most recent and highest quality evidence is necessary to guide clinical decision-making, with the 2021 practice guidance by the American Association for the Study of Liver Diseases providing key recommendations for the management of hyponatremia in patients with cirrhosis 1.

From the FDA Drug Label

Tolvaptan tablets are indicated for the treatment of clinically significant hypervolemic and euvolemic hyponatremia (serum sodium <125 mEq/L or less marked hyponatremia that is symptomatic and has resisted correction with fluid restriction), including patients with heart failure and Syndrome of Inappropriate Antidiuretic Hormone (SIADH) 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.

Treatment of Hyponatremia: Tolvaptan is indicated for the treatment of clinically significant hypervolemic and euvolemic hyponatremia. The starting dose is 15 mg once daily, which can be increased to a maximum of 60 mg once daily as needed to achieve the desired level of serum sodium.

• Key Points:
  • Tolvaptan is used to treat hyponatremia in patients with heart failure and SIADH.
  • The dose should be increased gradually to avoid too rapid correction of serum sodium.
  • Patients should be monitored closely for changes in serum sodium and volume status.
  • Tolvaptan should not be used in patients with autosomal dominant polycystic kidney disease (ADPKD) outside of the FDA-approved REMS.
  • The treatment should be initiated and re-initiated in a hospital setting where serum sodium can be monitored closely 2.

From the Research

Treatment of Hyponatremia

• The treatment of hyponatremia depends on the underlying cause, severity, and symptoms of the condition 3, 4, 5.
• For most patients, the approach to managing hyponatremia should consist of treating the underlying cause 3.
• Urea and vaptans can be effective treatments for the syndrome of inappropriate antidiuresis and hyponatremia in patients with heart failure, but have adverse effects 3.
• Hypertonic saline is reserved for patients with severely symptomatic hyponatremia, and its use should be guided by clinical guidelines to avoid overly rapid correction of serum sodium levels 3, 6, 5, 7.

Use of Hypertonic Saline

• Hypertonic saline has been used for the treatment of hyponatremia for nearly a century, and its use is recommended in patients with moderate or severe symptoms to prevent neurological complications 7.
• The administration of hypertonic saline can be effective in managing acute symptomatic hyponatremia, with a rapid increase in serum sodium concentration of 3 to 5 mmol/L being safe and efficacious 6.
• However, overly rapid correction of chronic hyponatremia can cause osmotic demyelination syndrome, a rare but severe neurological condition 3, 4, 5.

Management of Severe Hyponatremia

• Severely symptomatic hyponatremia is a medical emergency, and treatment with bolus hypertonic saline is recommended to reverse hyponatremic encephalopathy 3, 5.
• The goal of treatment is to increase the serum sodium level by 4 to 6 mEq/L within 1 to 2 hours, but by no more than 10 mEq/L within the first 24 hours 3.
• Desmopressin may be useful in curtailing the water diuresis responsible for rapid correction of hyponatremia, and its use can be considered in certain cases 5, 7.