From the Guidelines
Hypervolemic hyponatremia should be managed with fluid restriction to 1-1.5 L/day in patients who are clinically hypervolemic with severe hyponatraemia (serum sodium <125 mmol/L), as recommended by the most recent guidelines 1. The primary approach to treating hypervolemic hyponatremia involves addressing the underlying cause while carefully correcting sodium levels and managing fluid overload.
- The condition is characterized by low sodium levels in the blood (below 135 mEq/L) accompanied by excess total body water and sodium, resulting in edema.
- Common causes include heart failure, cirrhosis, and nephrotic syndrome, which all lead to decreased effective arterial blood volume, triggering antidiuretic hormone release despite overall fluid excess.
- Treatment options may include loop diuretics such as furosemide to promote water and sodium excretion, and in severe cases, 3% hypertonic saline may be administered with close monitoring to avoid rapid correction 1.
- Sodium levels should be corrected slowly, not exceeding 8 mEq/L in 24 hours to prevent osmotic demyelination syndrome.
- The use of aquaretic drugs, such as conivaptan and tolvaptan, has been studied in patients with cirrhosis and may be effective in correcting hyponatremia, but their use requires caution and further investigation is needed to determine their effectiveness and cost-effectiveness 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)
- Hypervolemic hyponatremia is a condition where the body has an excess of fluid and low sodium levels in the blood.
- Tolvaptan is indicated for the treatment of clinically significant hypervolemic hyponatremia, as stated in the drug label 2.
- The treatment should be initiated and re-initiated in a hospital where serum sodium can be monitored closely to avoid too rapid correction of hyponatremia.
- The usual starting dose for tolvaptan tablets is 15 mg administered once daily without regard to meals.
- The dose can be increased 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.
From the Research
Definition and Classification of Hyponatremia
- Hyponatremia is defined as a serum sodium level of less than 135 mEq/L 3
- It can be classified according to the volume status of the patient as hypovolemic, euvolemic, or hypervolemic hyponatremia 3, 4
Causes of Hypervolemic Hyponatremia
- Hypervolemic hyponatremia may be caused by congestive heart failure, liver cirrhosis, and renal disease 4
- It occurs as a consequence of an impairment in the renal capacity to eliminate solute-free water, leading to a non-osmotic hypersecretion of vasopressin (AVP) 5
- Advanced cirrhosis is a common cause of hypervolemic hyponatremia, with a reduction in effective arterial blood pressure contributing to the development of this condition 5
Symptoms and Complications of Hypervolemic Hyponatremia
- Symptoms of hypervolemic hyponatremia include swellings, ascites, distension of jugular veins, and the presence of unaccented rales in the lungs 6
- Hypervolemic hyponatremia is associated with increased morbidity and mortality in patients with cirrhosis, and it has also been associated with increased complications after liver transplantation 5
Treatment of Hypervolemic Hyponatremia
- The management of hypervolemic hyponatremia is based on fluid restriction 5
- Vaptans, oral selective vasopressin V2-receptor antagonists, and particularly tolvaptan, have been investigated as a pharmacological approach for the management of hypervolemic hyponatremia in cirrhosis 5
- Vasopressin receptor antagonists (VRAs) have shown promise for the treatment of hyponatremia, with significant increases in serum sodium concentration and response rate compared to placebo 7
- However, the use of VRAs has been associated with adverse events, including rapid sodium level correction, constipation, dry mouth, thirst, and phlebitis 7