Thyroid function and therapeutic efficacy of thyroxine in depression.

The authors administered 50-100 micrograms of thyroxine (T4) alone for 2 weeks to 20 patients with primary major depressive disorders, evaluated clinical changes, and compared the thyroid functions before and after the trial. The results showed a significant decrease in the Hamilton Rating Scale scores, and the efficacy of thyroid hormone alone was demonstrated against depression. It was also shown that this antidepressive effect varied widely from marked improvement to mild aggravation. The degree of clinical improvement had no significant relationship with sex, age, subtype of depression, and severity of symptoms before treatment. But it had significant positive correlations with the pre-trial T3, T4, T3 uptake, free T4 index and BMR. That is, patients with a higher pre-trial thyroid function showed a greater improvement. Thus, it was suggested that the antidepressive effects is closely associated with the mechanism which suppresses endogenous thyroid hormones.