What are the implications of hyponatremia (low sodium) with a level of 115 milliequivalents per liter (mEq/L)?

From the Guidelines

Sodium 115 is a severe case of hyponatremia that requires immediate medical attention to prevent osmotic demyelination syndrome (ODS) and other complications, and 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, as recommended by the American Association for the Study of Liver Diseases 1.

Management of Severe Hyponatremia

The management of severe hyponatremia, such as sodium 115, involves a multidisciplinary approach to prevent ODS and other complications.

• The use of hypertonic saline is reserved for short-term treatment of patients with symptomatic or severe hyponatremia or those with imminent liver transplant (LT) 1.
• Water restriction to 1,000 mL/day and cessation of diuretics is recommended in the management of moderate hyponatremia, and a more severe restriction of water intake with albumin infusion is recommended for severe hyponatremia (<120 mEq/L) 1.
• The use of vasopressin receptor antagonists in cirrhosis can raise serum sodium during treatment, but they should be used with caution only for a short term (≤30 days) 1.

Prevention of Osmotic Demyelination Syndrome (ODS)

To prevent ODS, the correction of chronic hyponatremia should be done slowly, with a goal rate of increase of serum sodium of 4-6 mEq/L per 24-hour period, not to exceed 8 mEq/L per 24-hour period 1.

• Severe hyponatremia (<120 mEq/L) at the time of LT increases the risk of ODS with LT, and multidisciplinary coordinated care may mitigate the risk of ODS 1.
• The serum sodium concentration at which fluid restriction should be instituted has not been well defined, but it is recommended when serum sodium is ≤125 mmol/L or its onset is rapid 1.

From the FDA Drug Label

The FDA drug label does not answer the question.

From the Research

Sodium Disorders

• Sodium disorders, including hyponatremia and hypernatremia, are common electrolyte disturbances in clinical medicine and are associated with increased rates of morbidity and mortality 2.
• Hyponatremia is defined by a serum sodium level of less than 135 mEq/L and most commonly results from water retention 3.
• Hypernatremia most often occurs because of water loss or inadequate water intake 2.

Diagnosis and Management

• The approach to managing hyponatremia should consist of treating the underlying cause, and patients should be categorized according to their fluid volume status (hypovolemic hyponatremia, euvolemic hyponatremia, or hypervolemic hyponatremia) 3.
• Hypovolemic hyponatremia is managed by rehydration with isotonic saline, while hypervolemic hyponatremia is managed by addressing the underlying cause 2.
• Euvolemic hyponatremia is managed by restricting free water intake, addressing the underlying cause, and occasionally with drugs (eg, vasopressin receptor antagonists) 2.
• Severely symptomatic hyponatremia is a medical emergency and should be treated with bolus hypertonic saline to reverse hyponatremic encephalopathy 3, 4.

Treatment Options

• Hypertonic saline has been used for the treatment of hyponatremia for nearly a century, and its use is recommended in patients with hyponatremia associated with moderate or severe symptoms 4.
• 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.
• Vasopressin receptor antagonists, also known as vaptans or aquaretics, are a new class of drugs that offer an additional treatment option for hyponatremic patients with euvolemic hyponatremia due to SIADH 5.