Iatrogenic hyponatremia in a patient with bipolar disorder

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Bipolar disorder is a chronic mental disorder, often with onset at a young age. An estimated 4.4% of US adults experience bipolar disorder at some time in their lives.¹ According to the National Comorbidity Survey Replication, the past-year prevalence of bipolar disorder in adults age ≥60 is 0.7%.¹ An estimated 83% of people with bipolar disorder have serious impairment, which is the highest percentage of serious impairment among mood disorders.¹ Bipolar I disorder affects men and women equally, whereas bipolar II disorder seems to occur more frequently in women.² Symptoms of bipolar disorder include episodes of mania, depression, and mixed states.²

A variety of medications—including mood stabilizers, lithium, and antipsychotics (Table 1,^3,4 and Table 2,⁴)—and somatic treatments such as electro­convulsive therapy and transcranial magnetic stimulation are used to manage the depressive and manic/mixed episodes of bipolar disorder. Treatment should be individualized based on the patient’s symptom severity, sensitivity, response to treatment, and preferences.

The most common reason for discontinuing a medication is intolerance to adverse effects. Some adverse effects are mild and may lessen over time. Others can be life-threatening. Thus, medications should be chosen carefully and started at low doses, and patients should be closely monitored for adverse effects at regular intervals.

Here I describe the case of a patient with bipolar disorder who developed hyponatremia while being treated with the second-generation antipsychotic lurasidone.

Continue to: CASE REPORT...