Hyponatremia Upon Resumption of Paroxetine Therapy

Abstract

We present a 79-year-old woman with severe hyponatremia secondary to resumption of treatment with paroxetine, a selective serotonin-reuptake inhibitor antidepressant. Confusion and fatigue followed re-initiation of paroxetine after a 3-month hiatus. Hyponatremia, serum hypoosmolality, and urine hyperosmolality strongly suggested the syndrome of inappropriate secretion of antidiuretic hormone. Hyponatremia was quickly resolved after discontinuation of paroxetine and initiation of intravenous normal saline infusion together with oral fluid restriction. This case underscores the importance of monitoring serum sodium in elderly patients taking paroxetine, whether this represents a new prescription or reintroduction of the drug.