Endocrine Abstracts

Objective: To determine the impact of combined antidepressant drugs and LT4 enhancers in treatment of patients with Major Depressive Disorder.

Method: We conducted a randomized, placebo-controlled trial to determine whether LT4 supplementation had any augmentation effect on selective serotonin reuptake inhibitors (SSRIs). The study involved 70 patients with major depressive disorder; patients with hypothyroidism were excluded. Of the participants, 38 were assigned to receive LT4, and 32 received placebo. All of the patients received SSRI – paroxetine (50%), sertraline (28%) and fluoxetine (22%). A total of 66 patients completed the three month study. We made weekly psychological evaluations using clinical scale HAM-D (Hamilton Depression Scale). Thyroid data, consisting of values for thyroid-stimulating hormone TSH and LT4, measured by radioimmunoassay were collected before and after treatment.

Results: A decrease in HAM-D score was observed in both groups, with a medium improvement of 12.3 points and a significant difference in favour of LT4 group. In the LT4 group, 30 patients (83.3%) responded to treatment compared with 21 patients (70%) in the placebo group. The onset of antidepressant effect was earlier in the LT4 group with an average response in 2 weeks. Those in the group receiving LT4 supplements had lower levels of LT4 and TSH after the study when compared to baseline. Final TSH values correlated strongly with response to treatment as measured by change in HAM-D scores.

Conclusion: Supplements of levothyronine (LT4) enhance the antidepressant effects of SSRIs. LT4 is efficacious as an enhancer of antidepressant therapy. Low TSH values correlated with greater improvement in depressive symptoms.