The syndrome of inappropriate antidiuretic hormone secretion (SIADH) represents the classic euvolemic hyponatremia where ADH secretion, despite the hypo-osmolality state, is not suppressed and is potentiated by several drugs (antineoplastic treatments, antidepressant such as selective serotonin reuptake inhibitors, antipsychotics, anti-epileptics such as carbamazepine, oxcarbazepine, eslicarbazepine, sodium valproate, lamotrigine, levetiracetam, and gabapentin) (11) or alternatively is oversecreted as the expression of a paraneoplastic syndrome. This evidence concerns the gene AVP and inappropriate ADH syndrome.