Hyponatremia is the most common
electrolyte abnormality encountered in clinical practice with wide-ranging prognostic implications in a variety of conditions. This review summarizes the available literature on the epidemiology of
hyponatremia in both hospitalized and ambulatory-based patients. Particular attention is given to
hyponatremia in the geriatric population, drug-induced
hyponatremia, exercise-associated
hyponatremia, and the medical costs of
hyponatremia. The frequency and outcomes of
hyponatremia in
congestive heart failure,
cirrhosis,
pneumonia, and human immunodeficiency virus
infection also are reviewed. Although the knowledge on
hyponatremia has expanded in the past few decades, the disorder largely remains an underdiagnosed condition. Substantial additional work is needed to improve the awareness of
hyponatremia among medical professionals. The advent of
vasopressin-receptor antagonists as a plausible treatment option for some forms of euvolemic and hypervolemic
hyponatremia now offers the opportunity to gain further insights into the prognostic impact of
hyponatremia and its management in various clinical settings.