Hyponatremia in heart failure.

Hyponatremia is the most common electrolyte abnormality found in hospitalized patients with heart failure. It may occur in patients who have hypovolemic, hypervolemic, or euvolemic state. It is usually not corrected by available therapies. It is a major predictor of prognosis, and correction of hyponatremia can be effectively accomplished by vasopressin antagonists. However, it still remains to be seen whether the normalization of serum sodium with vasopressin antagonists will also lead to an improved long-term prognosis.