A condition of hyponatremia and renal salt loss attributed to overexpansion of body fluids resulting from sustained release of ANTIDIURETIC hormones which stimulates renal resorption of water. It is characterized by normal kidney function, high urine OSMOLALITY, low serum osmolality, and neurological dysfunction. Etiologies include ADH-producing neoplasms, injuries or diseases involving the hypothalamus, the pituitary gland, and the lung. This syndrome can also be drug-induced.