Marilyn Novell Bulloch, Pharm.D., BCPS, FCCM, Aimee Patterson, Pharm.D., Sharronda Davis, Pharm.D.
What is Known and Objective: Acute hyponatremia occurs when serum sodium declines to <135 mEq/L within
a 48-hour period. Tolvaptan, a vasopressin receptor antagonist, causes aquaresis without increased
sodium loss.
Details of the Case: A77 year-old male, with a history of glioblastoma, presented with a five-day history of
weakness. Serum sodium on admission was 115 mEq/L, and normal saline was started. The following morning
serum sodium was 114 mEq/L. Tolvaptan 15mg was given. By hospital day 3, the serum sodium increased to
124 mEq/L following titrated tolvaptan doses.
What is New and Conclusion: Based on these results, tolvaptan may have a role in the treatment of acute
hyponatremia.
