Isolated syndrome of inappropriate antidiuresis (SIAD) after Transphenoidal surgery of a non-functioning pituitary...

Disorders of water balance, including arginine vasopressin deficiency (AVP-D) and syndrome of inappropriate antidiuresis (SIAD), are common postoperative complications following pituitary surgery. While AVP-D typically occurs as an isolated condition, SIAD may also present independently.

We describe the case of a patient with a non-functioning pituitary adenoma who underwent transsphenoidal surgery. On postoperative day 7, she developed isolated SIAD, characterized by a plasma sodium level of 113 mmol/L, normovolemia, urine osmolality of 364 mOsm/kg, and urine sodium concentration of 50 mmol/L. A daily fluid restriction of 800 mL resulted in the resolution of hyponatremia within 48 h.

Water balance disorders following pituitary surgery are often unpredictable. This case highlighs the importance of close postoperative clinical and biochemical monitoring. Vigilance is essential, even in the absence of AVP-D, to ensure early detection and management of potentially severe complications such as SIAD.