Study on the effectiveness and safety of the treatment of mild-moderate symptomatic hyponatremia due to syndrome of inappropriate secretion of antidiuretic hormone (SIADH) with Tolvaptan vs fluid restriction in patients who underwent transsphenoidal surgery for hypothalamic-pituitary disorders.

INTERVENTION: Trade Name: SAMSCA*10CPR 15MG Pharmaceutical Form: Tablet INN or Proposed INN: TOLVAPTAN CAS Number: 150683‐30‐0 Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 15‐ CONDITION: Mild‐moderate symptomatic hyponatremia due to syndrome of inappropriate secretion of antidiuretic hormone (SIADH) ; MedDRA version: 14.1 Level: SOC Classification code 10014698 Term: Endocrine disorders System Organ Class: 10014698 ‐ Endocrine disorders Therapeutic area: Diseases [C] ‐ Hormonal diseases [C19] PRIMARY OUTCOME: Main Objective: Evaluation of effectiveness and safety of Tolvaptan in the treatment of mild‐moderate symptomatic hyponatremia due to syndrome of inappropriate secretion of antidiuretic hormone (SIADH) in patients who underwent transsphenoidal surgery for hypothalamic‐pituitary disorders. Primary end point(s): Normalization of serum sodium levels in patients affected by sindrome of inappropriate secretion of antidiuretic hormone Secondary Objective: Evaluation of mean resolution time of hyponatremia in the two groups of treatment (tolvaptan vs fluid resctriction). Timepoint(s) of evaluation of this end point: Between 1 and 10 days SECONDARY OUTCOME: Secondary end point(s): Reduction of mean resolution time of hyponatremia in patients reated with Tolvaptan in respect to patients treated with fluid restriction Timepoint(s) of evaluation of this end point: Between 1 and 10 days INCLUSION CRITERIA: ‐ age >18 ‐ admission to Neurosurgery Unit for pituitary surgery ‐ Serum sodium levels lower than 135 mEq/l and higher than 120 mEq/l ‐ One or more symptoms of hyponatremia ‐ Euvolemic patient ‐ Informed consent Are the trial subjects under 18? no Number of subjects for this age range: 0 F.1.2 Adults (18‐64 years) yes F.1.2.1 Number of subjects for this age range 10 F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range 5