Case Report of SIADH Associated With Escitalopram Use

The authors report a case of syndrome of inappropriate antidiuretic hormone (SIADH) associated with the use of escitalopram in an elderly female patient. A 97-year-old white female was admitted to the hospital for a suspected vertebral fracture and hyponatremia. Her serum sodium concentration was 113 mEq/L (113 mmol/L) at admission. She was started on escitalopram 5 mg daily 1 week prior to admission for anxiety. During admission, her laboratory tests revealed serum hyponatremia and hypo-osmolality and urine hyperosmolality and hypernatremia. Her escitalopram was stopped, and she was diagnosed with syndrome of inappropriate antidiuretic hormone. She was treated with hypertonic (3%) saline. She was discharged 1 week later with a serum sodium concentration of 121 mEq/L (121 mmol/L). There have been hundreds of case reports of SIADH associated with selective serotonin reuptake inhibitors (SSRIs), including 5 cases associating escitalopram with syndrome of inappropriate antidiuretic hormone. The median time to onset of SIADH after initiating SSRIs is approximately 2 weeks. Risk factors include advanced age, concomitant diuretic use, low baseline sodium, and low body mass index. Treatment options include fluid restriction, normal saline, diuretics, hypertonic saline, and discontinuing the SSRI. The authors conclude that elderly patients receiving escitalopram or other SSRIs should be monitored carefully for SIADH in the first couple of weeks of treatment and with dose increases, especially if other risk factors are present.