SIAD, which is due in most cases to arginine vasopressin (AVP) release not caused by increased serum osmolality (hence the previous name Syndrome of Inappropriate Anti Diuretic Hormone secretion), may be secondary to a number of different pathologies (e.g. tumors, central nervous system diseases, pulmonary diseases), as well as to treatment with different drugs. Here, AVP is linked to central nervous system disorder.