Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH, SIAD) and the Clinical Management of Hyponatremia

Oversecretion of antidiuretic hormone (ADH, vasopressin) is a common cause of hyponatremia in both hospitalized and ambulatory patients. In the physiological setting, antidiuretic hormone is produced by the hypothalamus and released by the posterior pituitary. However, ADH can also be secreted by tumors as a paraneoplastic endocrine syndrome, or can be increased due to various pathologic processes and use of drugs. This chapter discusses hyponatremia, its clinical management, and the syndrome of inappropriate ADH secretion.