Antidiuretic hormone (ADH), or vasopressin, is a substance produced naturally by the hypothalamus and released by the pituitary gland. The hormone controls the amount of water your body removes.
Ectopic ADH secretion is the release of ADH from an abnormal location within the body. Ectopic means "out of place."
SIADH; Syndrome of inappropriate antidiuretic hormone secretion
Causes, incidence, and risk factors
The most common cause of ectopic ADH secretion is cancer. Certain lung cancers, as well as some head and neck tumors, are the most common cancers that cause this problem. In rare cases, many other tumors may cause ectopic ADH secretion.