Thyroid hormone treatment of depression.

The use of thyroid hormones in the treatment of depression is reviewed. The studies examining the use of triodothyronine (T3) alone as well as combination with antidepressants are discussed. The data suggest that there is little evidence that T3 alone has antidepressant efficacy but that this hormone may be used to enhance therapeutic effects of antidepressants in treatment refractory depressed patients. The different theories to explain the antidepressant effects of T3 are summarized.