Desvenlafaxine is a prescription medication approved for the treatment of major depressive disorder in adults. Hyponatremia secondary to inappropriate secretion of antidiuretic hormone (SIADH) is a possible side effect in patients receiving serotonin-norepinephrine reuptake inhibitors (SNRIS)

To report a case of SIADH associated with desvenlafaxine.

We present a 80-year-old female patient who required hospitalization due to an episode of psychotic depression. During the hospitalization, the patient developed hyponatremia after commencing treatment with desvenlafaxine. The serum sodium at this time was 117 mmol/L, serum osmolality was 249 mosmol/kg, urine osmolality 395 mosmol/kg and urine sodium 160 mmol/L, consistent with a diagnosis of SIADH. Desvenlafaxine was ceased and fluid restriction implemented. The mental status improved, and electrolyte studies 6 days later revealed serum sodium and osmolality values of 135 mEq/L during treatment with duoxetine.

SIADH has been reported with a range of antidepressants in elderly patients. This case report suggests that desvenlafaxine might cause clinically significant hyponatremia. Close monitoring is recommended in patients starting therapy with antidepressant treatment to study and prevent possible adverse effects.

The authors have not supplied their declaration of competing interest.