Cancer-Related Hyponatremia: Enhancing Recognition and Improving Management

Abstract

In this interactive continuing medical education (CME) web-based activity, an expert faculty describes the diagnosis and management of hyponatremia in patients with cancer (online access available at: http://www.cmeelsevier.com/hyponatremia/571). Hyponatremia is classified according to the tonicity of plasma, the severity of the decrease in sodium level, and neurologic symptoms. The incidence of hyponatremia in patients with cancer varies widely depending on the type of cancer and can be found in as many as 47% of patients. The most common types of cancer with a significant incidence of hyponatremia include solid tumors, such as small-cell lung cancer, pancreatic cancer, gastric cancer, and renal cell cancer, as well as some hematologic malignancies. Management of hyponatremia is crucial, because it has been associated with a diminished response to cancer treatment and because patients with hyponatremia have higher mortality rates and longer hospital stays. Although the cause of hyponatremia is often multifactorial, the syndrome of inappropriate antidiuretic hormone secretion (SIADH) is one of the most common causes in patients with cancer. Treatment depends on symptom severity, whether the hyponatremia is acute or chronic, and the extracellular volume status. The standard initial therapy for patients with SIADH in euvolemic hyponatremia is fluid restriction. Pharmacologic therapy with a vasopressin receptor antagonist might be appropriate when fluid restriction is insufficient.