Unlike the mixed pattern of diuresis observed in the OPCABG patients in our study—characterized predominantly by water diuresis with hyperosmolar features—neurosurgical and trans-sphenoidal pituitary procedures are more commonly associated with oliguria and hypotonic hyponatremia due to excessive AVP secretion, presenting a typical SIADH-like profile [23]. This evidence concerns the gene AVP and Hyponatremia.