Antidepressant-induced hyponatraemia in the aged. Avoidance and management strategies.

Antidepressant-induced hyponatraemia, while relatively uncommon, is an important clinical problem with serious consequences. Most antidepressants have been associated with hyponatraemia. Although the exact mechanism by which abnormalities of serum sodium level are produced is not known, most of the patients described in case reports meet the accepted criteria for the syndrome of inappropriate antidiuretic hormone secretion. Symptoms of hyponatraemia can mimic depression or psychosis, so awareness of this syndrome and periodic monitoring of serum electrolytes are important for early recognition. Stopping the medication and assuring normal extracellular fluid volume are the mainstay of treatment; rarely, intravenous infusion of hypertonic saline is required. After correcting the metabolic abnormalities, options for treatment of depression include: rechallenging with the same medication or initiating another antidepressant while carefully monitoring serum sodium level, or considering electroconvulsive therapy, if warranted by the clinical condition.