Effectiveness of Tolvaptan Treatment in Hyponatremic Patients

Objective: Non-peptide vasopressin receptor antagonists (vaptans) are effective at increasing sodium in euvolemic and hypervolemic states and appear safe. We aimed to evaluate the efficacy of tolvaptan in euvolemic or hypervolemic hyponatremic patients. Methods: The study included 9 hyponatremic (serum sodium level <125 mmol/L) patients. Serum potassium levels of all patients were normal and there was no acid-base disturbance. Patients with hypovolemic status and hepatic dysfunction were excluded from the study. Clinical and laboratory data of patients were obtained before and after tolvaptan (7.5 mg/day) treatment. Results: The median age of patients (6 females, 3 males) was 66.3 years (range, 56-82). The mean sodium levels before tolvaptan treatment were 120.5 mEq/L (SD 2.2, range, 116-124). The mean sodium levels increased significantly to 132.6±4.0 mEq/L (range, 125-140) after tolvaptan treatment at 2.7±1.3 days (range, 2-6) (p<0.001). Hyponatremia did not recur after tolvaptan treatment. We did not observe serious adverse event related with tolvaptan treatment. Conclusion: Hyponatremia was a common problem, and tolvaptan can treat hyponatremia effectively and safely in patients with euvolemic or hypervolemic hyponatremia.