The use of thyroid hormones in the treatment of depression is reviewed
. The studies examining the use of triodothyronine (T-3) alone as well
as in combination with antidepressants are discussed. The data sugges
t that there is little evidence that Tg alone has antidepressant effic
acy but that this hormone may be used to enhance therapeutic effects o
f antidepressants in treatment refractory depressed patients. The diff
erent theories to explain the antidepressant effects of T-3 are summar
ized.