Amiodarone-Associated Depression

Abstract

Objective:

To report a case of depression secondary to or aggravated by amiodarone-induced hypothyroidism.

Case Summary:

An 84-year-old white man was admitted to a psychiatric unit with severe depression approximately seven months after amiodarone had been initiated to treat paroxysmal supraventricular tachycardia. On admission, the thyroid-stimulating hormone (TSH) concentration was 11.50 μU/mL (normal 0.17–4.00) and the total thyroxine concentration was 3.9 μg/dL (4.0–11.0). About 21 months before initiation of amiodarone therapy, the TSH concentration was 2.4 μU/mL; this was the only previous TSH result available. Seven days after admission, thyroxine (levothyroxine) 25 μg/d was started. Twenty-eight days after admission, the patient's mood had improved, and the TSH concentration (2.67 μU/mL) was within normal range. The patient was discharged four days later.

Discussion:

Amiodarone contains 37.2% iodine. This is a greatly increased iodine load compared with normal intake. Amiodarone may therefore have three possible effects on thyroid function: (1) the serum concentration of thyroid hormones in clinically euthyroid patients may change, complicating assessment; (2) hyperthyroidism may occur (1–5% of patients); and (3) hypothyroidism may occur (6–10% of patients). Thus, thyroid function should be checked at least every six months. The elevated TSH concentration could indicate mild hypothyroidism or possibly be a symptom of the depressive illness. Furthermore, our patient's mood appeared to improve after he had received six to seven weeks of treatment with fluoxetine; he had also experienced depressive episodes throughout his life. Thus, particularly because the TSH concentration was only moderately raised, it is possible that amiodarone-induced hypothyroidism worsened rather than caused the depressive episode. The usual treatment for amiodarone-induced hypothyroidism is continuation of amiodarone and initiation of thyroxine at a dosage of 25–50 μg/d.

Conclusions:

This case illustrates the need to be vigilant for amiodarone-induced hypothyroidism, which may cause depression or exacerbate an underlying depressive illness. Supplemental treatment with levothyroxine may effect a rapid mood response.