Management of Chronic Asymptomatic Hyponatremia

Bae, Eun Hui

Abstract

Hyponatremia is a common clinical problem in hospitalized patients and nursing home residents. It may also occur in healthy athletes after endurance exercise. The majority of patients with hyponatremia are asymptomatic and do not require immediate correction of the hyponatremia. While mild hyponatremia has traditionally been considered benign, symptomatic hyponatremia is a medical emergency requiring rapid correction to prevent the worsening of brain edema. However, it has been suggested that mild hyponatremia may be associated with gait disturbance, attention deficits, and an increased risk of falls, which may result in fracture, and its presence predicts a poor prognosis. The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is among the most frequent causes of chronic hyponatremia. Hyponatremia must be corrected slowly (<10~12 mmol/L within the first 24 h, and <18 mmol/L within the first 48 h) to avoid osmotic myelinolysis. Fluid restriction and demeclocycline are the treatments for chronic hyponatremia used most widely. However, fluid restriction is of limited use because of poor long-term compliance and demeclocycline lacks broad availability. In controlled clinical trials vaptans (a vasopressin receptor antagonist) was efficacious in mild to moderate SIADH with an acceptable safety profile. However, its long-term use is currently impractical and more data are needed.