Tolvaptan for the Prevention of Delayed Hyponatremia after Surgery in Patients with Pituitary Macroadenoma: a Multicenter, Single-Blind, Randomized Controlled Clinical Trial

INTERVENTION: tolvaptan group:Orally administered tolvaptan;placebo group:oral placebo; CONDITION: Delayed hyponatremia after pituitary tumor surgery PRIMARY OUTCOME: Incidence of hyponatremia on postoperative day 7; SECONDARY OUTCOME: Incidence of hypopituitarism (pituitary‐adrenal function, pituitary‐thyroid function);Incidence of adverse drug reactions (ADRs); INCLUSION CRITERIA: 1. Age 18–70 years; 2. Sexr No restriction; 3. Tumor diameter >=1 cm; 4. First‐time endoscopic transsphenoidal surgery (eTSS); 5. Pathologically confirmed pituitary adenoma (all subtypes); 6. Normal serum sodium level on postoperative day 4; 7. Written informed consent obtained.