Sodium disturbances are common in patients presenting with neurologic disease. However, postoperative development of sodium dysregulation may be seen after transphenoidal surgery. This chapter presents a case study of a 45-year-old male with a 1-year history of right temporal anopsia and impotence underwent a successful transphenoidal resection of a 21 mm suprasellar mass under general anesthesia. Due to the clinical suspicion of central diabetes insipidus (DI), he was treated conservatively with liberal access to oral intake of water and intravenous fluids. Perioperative central DI is a common finding in patients undergoing pituitary surgery. Preoperative DI can be part of a panhypopituitarism syndrome in patients with large pituitary prolactinomas or nonprolactinomas. The clinical manifestation of central DI ranges from mild thirst to significant polyuria, polydipsia, dehydration and, if severe, hypotension. Serum sodium has to be followed during vasopressin administration because the excessive retention of free water can lead to hyponatremia.