What are the causes and treatments of hyponatremia (low sodium levels)?

From the Guidelines

Hyponatremia in patients with cirrhosis and ascites should be managed based on the etiology, chronicity, severity, and urgency, with the goal of correcting sodium levels gradually to prevent osmotic demyelination syndrome (ODS) 1. The management of hyponatremia in cirrhotic patients depends on several factors, including the severity and chronicity of the condition.

• For acute hyponatremia, rapid correction is recommended to prevent cerebral edema, while chronic hyponatremia requires a more gradual correction to avoid ODS 1.
• The treatment of hypovolemic hyponatremia involves discontinuing diuretics and laxatives and providing fluid resuscitation with 5% IV albumin or crystalloid solution, preferably lactated Ringer's solution 1.
• For euvolemic hyponatremia, management should be based on the underlying cause, while hypervolemic hyponatremia requires fluid restriction, reduction or discontinuation of diuretics and laxatives, administration of hyperoncotic albumin, and/or vasopressin receptor antagonists (“vaptans”) 1. Key considerations in the management of hyponatremia include:
• Avoiding overcorrection to prevent ODS, with a goal of increasing serum sodium by 4-6 mEq/L per 24-hour period, not to exceed 8 mEq/L per 24-hour period 1.
• Using vasopressin receptor antagonists with caution and only for short-term treatment (≤30 days) 1.
• Reserving hypertonic saline for short-term treatment of patients with symptomatic or severe hyponatremia or those with imminent liver transplantation (LT) 1. By following these guidelines, clinicians can effectively manage hyponatremia in patients with cirrhosis and ascites, minimizing the risk of complications and improving patient outcomes 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) 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. Osmotic demyelination syndrome is a risk associated with too rapid correction of hyponatremia (e.g., > 12 mEq/L/24 hours). Tolvaptan is used to treat hyponatremia. The correction of serum sodium should be done slowly to avoid osmotic demyelination syndrome, which can cause serious neurologic sequelae. In susceptible patients, including those with severe malnutrition, alcoholism or advanced liver disease, slower rates of correction may be advisable 2.

From the Research

Definition and Prevalence of Hyponatremia

• Hyponatremia is defined as a serum sodium level of less than 135 mEq/L 3, 4, 5.
• It is the most common electrolyte disorder, affecting approximately 5% of adults and 35% of hospitalized patients 3, 5.
• Hyponatremia can lead to a wide spectrum of clinical symptoms, from mild to severe or even life-threatening, and is associated with increased mortality, morbidity, and length of hospital stay 3, 5, 6.

Symptoms and Signs of Hyponatremia

• Symptoms and signs of hyponatremia range from mild and nonspecific (such as weakness or nausea) to severe and life-threatening (such as seizures or coma) 3, 4.
• Mild symptoms include nausea, vomiting, weakness, headache, and mild neurocognitive deficits 4.
• Severe symptoms of hyponatremia include delirium, confusion, impaired consciousness, ataxia, seizures, and, rarely, brain herniation and death 4.

Diagnosis and Management of Hyponatremia

• The approach to managing hyponatremia should consist of treating the underlying cause 3.
• Patients should be categorized according to their fluid volume status (hypovolemic hyponatremia, euvolemic hyponatremia, or hypervolemic hyponatremia) 3, 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, 7.
• Severely symptomatic hyponatremia is a medical emergency and should be treated with bolus hypertonic saline to reverse hyponatremic encephalopathy 3, 4.

Treatment Options

• Hypovolemic hyponatremia is treated with normal saline infusions 4.
• Euvolemic hyponatremia is treated by restricting free water consumption or using salt tablets or intravenous vaptans 4.
• Hypervolemic hyponatremia is treated primarily by managing the underlying cause (e.g., heart failure, cirrhosis) and free water restriction 4.
• Vasopressin receptor antagonists (VRA) can be used to induce urinary dilution and increase serum sodium concentration in patients with euvolemic and hypervolemic hyponatremia 7.