Wednesday August 1, 2007


Q; 72 year old female with no significant past medical history has been admitted from ER to ICU with progressive mental status change over last 3 days. Only significant finding in workup is Na+ of 123 mEq/liter. The only pertinent history is start of a new anti-depressant medication about 2 weeks ago. Per son, there is no sign of drug over-dose ?

A; Anti-depressants' associated hyponatremia.One of the significant but less know side effect of anti-depressants, mostly SSRIs is hyponatremia. Exact mechansism is unknown but it causes SIADH (Syndrome of Inappropriate Antidiuretic Hormone). It has also been reported with 'atypical' anti-depressents' (venlafaxine, trazodone, maprotiline, nefazodone, bupropion) as well as with tricyclic antidepressants (TCAs) and monamine oxidase inhibitors (MAOIs).When prescribing antidepressants particularly to elderly patients, consideration of hyponatremia should be kept in mind. Patients who develop mental status change need prompt assessment of electrolytes' status. Patients already at risk of the SIADH (such as cancer) should be prescribed anti-depressent with caution and close followup.


Related previous pearl: ANTIDEPRESSANTS' AND SEROTONIN SYNDROME


References: click to get abstract/artice

1. Hyponatremia in the psychiatric population: a review of diagnostic and management strategies. Psychiatr Ann 2003; 33:318–325

2. Hyponatremia secondary to antidepressants. Psychiatr Ann 2003; 33:333–339

3. Hyponatremia in elderly psychiatric patients treated with selective serotonin reuptake inhibitors and venlafaxine: a retrospective controlled study in an inpatient unit. Int J Geriatr Psychiatry 2002; 17:231–237

4. Hyponatremia with venlafaxine. Ann Pharmacother 1998; 32:49–50

5. Severe symptomatic hyponatremia during citalopram therapy - a case report - BMC Nephrology 2004, 5:2