Objective: The objective of this review is to discuss triiodothyronine's (T3, liothyronine) mechanism of action, efficacy in enhancement and augmentation trials, and dosing and safety considerations for the treatment of depression. Method: A literature search of PubMed was performed using search terms depression, augmentation, antidepressant, and liothyronine. Only English-language studies of subjects with unipolar depression were included from the past 50 years. Results: Most studies have shown that liothyronine is an efficacious enhancement and augmentation strategy for depression in combination with antidepressants, primarily tricyclic antidepressants and selective serotonin reuptake inhibitors. Conclusion: With appropriate baseline and follow-up safety monitoring, liothyronine augmentation can be a safe and effective treatment for unipolar depression. Larger studies of longer duration assessing liothyronine efficacy with serotonin norepinephrine reuptake inhibitors and multimodal antidepressants are needed.
Keywords: T3; Triiodothyronine; augmentation; enhancement; liothyronine; treatment-resistant depression.