What is the management of severe hyponatremia (low sodium level) in a 92-year-old patient?

From the Guidelines

Immediate hospitalization in an intensive care unit is essential for a 92-year-old patient with severe hyponatremia (sodium level of 23 mEq/L), and treatment should begin with careful sodium correction at a rate not exceeding 6-8 mEq/L in the first 24 hours and 10-12 mEq/L in the first 48 hours to avoid osmotic demyelination syndrome, as recommended by the most recent guidelines 1.

Key Considerations

• The patient's severe hyponatremia requires prompt attention to prevent further complications, such as cerebral edema and seizures.
• Initial management includes 3% hypertonic saline infusion at 1-2 mL/kg/hour with frequent serum sodium monitoring every 2-4 hours to adjust the rate accordingly, as supported by recent studies 1.
• If the patient has seizures or severe neurological symptoms, a 100 mL bolus of 3% saline may be administered over 10-15 minutes, which can be repeated if symptoms persist.
• Simultaneously, the underlying cause must be identified and addressed, whether it's medication-induced, SIADH, heart failure, liver disease, or other conditions.

Management Options

• Fluid restriction to 800-1000 mL/day is typically implemented to help manage hyponatremia.
• For chronic hyponatremia management after initial correction, options include:
  • Oral sodium chloride tablets
  • Loop diuretics like furosemide 20-40 mg daily
  • Vasopressin receptor antagonists such as tolvaptan (starting at 15 mg daily) if appropriate, as recommended by recent guidelines 1.

Monitoring and Precautions

• Careful monitoring is crucial in elderly patients due to their increased risk of complications from both hyponatremia and its correction, including altered mental status, falls, and osmotic demyelination syndrome.
• The patient's serum sodium levels should be closely monitored to avoid overcorrection and minimize the risk of osmotic demyelination syndrome, as emphasized by recent studies 1.

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.

For a 92-year-old patient with a sodium level of 23, tolvaptan may be considered as a treatment option for hyponatremia.

• The initial dose of tolvaptan is 15 mg once daily, and it can be increased 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.
• It is essential to monitor serum sodium levels closely, especially in patients whose serum sodium levels become normal, to ensure that serum sodium remains within normal limits.
• Hypernatremia is a potential risk, and management may include dose decreases or interruption of tolvaptan treatment, combined with modification of free-water intake or infusion 2.

From the Research

Management of Severe Hyponatremia

• The management of severe hyponatremia in a 92-year-old patient with a sodium level of 23 mEq/L requires careful consideration to avoid osmotic demyelination syndrome (ODS) 3, 4.
• Rapid correction of severe hyponatremia carries the risk of ODS, and expert opinion recommends that serum sodium level not be increased by more than 10-12 mEq/L in any 24-hour period and/or 18 mEq/L in any 48-hour period 4.
• The use of hypertonic saline and desmopressin has been proposed as a simple strategy for safe correction of severe hyponatremia, with desmopressin helping to prevent overcorrection of the hyponatremia 4.

Treatment Approaches

• The treatment of hyponatremia depends on the presence and severity of symptoms, with brain herniation being a concern when severe symptoms are present, and current guidelines recommending immediate treatment with hypertonic saline 5.
• In the absence of significant symptoms, the concern is neurologic sequelae resulting from rapid correction of hyponatremia, which is usually the result of a large water diuresis, and desmopressin may be useful to effectively curtail the water diuresis responsible for rapid correction 5.
• Minocycline has been shown to prevent ODS associated with aquaresis, and may be a useful adjunct in the treatment of severe hyponatremia 6.

Diagnostic and Therapeutic Strategies

• A physiological approach to determine if hyponatremia is hypotonic, if it is mediated by arginine vasopressin, and if arginine vasopressin secretion is physiologically appropriate is recommended 5.
• The diagnosis, evaluation, and treatment of hyponatremia require a comprehensive approach, taking into account the diverse etiologies and comorbidities associated with this disorder, and expert panel recommendations have been developed to guide clinicians in the management of hyponatremia 7.