The therapeutic use of triiodothyronine and high dose thyroxine in psychiatric disorder.

An intimate association between disturbances of thyroid hormone homeostasis and behavior has been recognized for a long time already: Hyper- and hypothyroidism can induce disturbances of mood and intellectual function (in severe cases even psychosis can be mimicked). Reciprocally many psychiatric disturbances, such as major depression and manic depressive disease have associated with them disturbances of peripheral thyroid hormone metabolism. Approximately 10% of depressed persons seem to have subclinical hypothyroidism and another approximately 35% have a blunted TSH response to TRH. The use of lithium clearly increases these numbers. In some cases a positive correlation between elevated T4 and the speed of response to antidepressant drugs has been reported. Patients with manic depressive disease respond less well to treatment with lithium when they have a so called "rapid cycling disorder" (defined as more than 4 episodes of disturbed behavior a year). These patients were shown to have a comparably high incidence (up to 50%) of mild subclinical hypothyroidism. In an open study of 11 patients (10 females--9 of them premenopausal--1 male) with rapid cycling disorder adjunctive treatment with TSH suppressive doses of T4 (T4 levels at approximately 150% of normal) reduced the manic and depressive phases in both amplitude and frequency and even led to remittance in some patients. T4 treatment was begun only after stable "therapeutic" blood levels of lithium carbonate and/or anticonvulsants have been reached, since it has been shown that T4 therapy alone can precipitate dysphoric manic like symptoms which require treatment with neuroleptics. Careful evaluation of possible side effects like osteoporosis revealed surprisingly an even higher bone density in treated patients.(ABSTRACT TRUNCATED AT 250 WORDS)