Syndrome of inappropriate antidiuretic hormone secretion associated with desvenlafaxine

Objective To report a case of syndrome of inappropriate anti-diuretic hormone (SIADH) secretion associated with desvenlafaxine. Case summary A 57-year-old female with hyponatraemia. Her medications included desvenlafaxine, and symptoms included nausea, anxiety and confusion. The serum sodium at this time was 120 mmol/L, serum osmolality was 263 mosmol/kg, urine osmolality 410 mosmol/kg and urine sodium 63 mmol/L, consistent with a diagnosis of SIADH. Desvenlafaxine was ceased and fluid restriction implemented. After 4 days the sodium increased to 128 mmol/L and fluid restriction was relaxed. During her further 3 weeks inpatient admission the serum sodium ranged from 134 to 137 mmol/L during treatment with mirtazapine. Discussion SIADH has been widely reported with a range of antidepressants. This case report suggests that desvenlafaxine might cause clinically significant hyponatremia. Conclusions Clinicians should be aware of the potential for antidepressants to cause hyponatremia, and take appropriate corrective action where necessary.