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T33.4

T3 (Liothyronine) Research

Mostly mechanism / observational

106 peer-reviewed studies

What the evidence says

Mostly mechanism / observational

Most T3 (Liothyronine) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.

Most evidence is from high-quality meta-analyses and randomised trials published 1979–2026 with a typical study size of 2,007 participants.

Based on 106 studies · 16 meta-analyses · 83 RCTs · 2,013 total participants

Confidence

High confidence

By outcome

Thyroid & hypothyroidism (approved use)
Mostly mechanism / observational91 studies
Cardiac & arrhythmia
Mostly mechanism / observational5 studies
Weight & fat loss (off-label)T3 genuinely increases basal metabolic rate and thermogenesis — the mechanism behind its off-label fat-loss reputation, though weight lost on supraphysiologic T3 comes disproportionately from lean mass · Weeks
Mostly mechanism / observational3 studies
Lean mass & muscle loss
Mostly mechanism / observational3 studies
Bone health
Too few graded studies2 studies
Safety profile
Too few graded studies2 studies

Steady research

20 studies in the last 5 years · Latest meta-analysis: 2026

197920022026

1Meta-Analysis2006

Grozinsky-Glasberg S, Fraser A, Nahshoni E, Weizman A, Leibovici L · J Clin Endocrinol Metab (2006)

T3 (Liothyronine) Research

Mostly mechanism / observational

Thyroxine-triiodothyronine combination therapy versus thyroxine monotherapy for clinical hypothyroidism: meta-analysis of randomized controlled trials.

Evaluating the effectiveness of combined T4 and T3 therapy or desiccated thyroid versus T4 monotherapy in hypothyroidism: a systematic review and meta-analysis.

Does thyroid supplementation accelerate tricyclic antidepressant response? A review and meta-analysis of the literature.

Thyroxine alone or thyroxine plus triiodothyronine replacement therapy for hypothyroidism.

Thyroid Hormone (Triiodothyronine) Therapy in Children After Congenital Heart Surgery: A Meta-Analysis.

Ischemic Stroke and Impact of Thyroid Profile at Presentation: A Systematic Review and Meta-analysis of Observational Studies.

Triiodothyronine augmentation in the treatment of refractory depression. A meta-analysis.

Treatment of Hypothyroidism That Contains Liothyronine is Associated With Reduced Risk of Dementia and Mortality.

The Effectiveness of Thyroid Hormone Replacement Therapy on Heart Failure and Low-Triiodothyronine Syndrome: An Updated Systematic Review and Meta-analysis of Randomized Controlled Trials.

Combined therapy with levothyroxine and liothyronine for hypothyroidism.

Treatment of clinical hypothyroidism with thyroxine and triiodothyronine: a literature review and metaanalysis.

Risk of Death and Adverse Effects in Patients on Liothyronine: A Multisource Systematic Review and Meta-analysis.

Triiodothyronine Supplementation for Children Undergoing Cardiopulmonary Bypass: A Meta-Analysis.

Treatment Preferences in Patients With Hypothyroidism.

Efficacy and safety of triiodothyronine supplementation in patients with major depressive disorder treated with specific serotonin reuptake inhibitors.

REVIEW: Treatment of hypothyroidism with combinations of levothyroxine plus liothyronine.

A Systematic Review of Clinical Practice Guidelines' Recommendations on Levothyroxine Therapy Alone versus Combination Therapy (LT4 plus LT3) for Hypothyroidism.

LT4/LT3 Combination Therapy vs. Monotherapy with LT4 for Persistent Symptoms of Hypothyroidism: A Systematic Review.

Hypothyroidism (primary).

Acute Effects of Liothyronine Administration on Cardiovascular System and Energy Metabolism in Healthy Volunteers.