Liothyronine (T3) is the biologically active thyroid hormone. Binds thyroid hormone receptors (TRα, TRβ) in the nucleus, directly modulating gene transcription. Controls basal metabolic rate (BMR), thermogenesis, cardiac output, protein synthesis, and cholesterol metabolism. T3 is predominantly produced by peripheral deiodination of T4 (thyroxine) by deiodinase enzymes. In research, T3 is used as the active standard for thyroid function studies, metabolic rate manipulation, and thyroid receptor pharmacology — cutting through T4→T3 conversion variability.
Also Known As
Liothyronine, Cytomel, 3,5,3′-Triiodothyronine
Compound Class
Thyroid hormone — active T3 form
Molecular Formula
C₁₅H₁₂I₃NO₄
Molecular Weight
650.97 Da
CAS Number
6893-02-3
Half-Life
~2.5 days
Research Applications
Metabolic Rate / Thermogenesis Research
T3 directly upregulates Na⁺/K⁺-ATPase, uncoupling protein (UCP), and mitochondrial biogenesis genes — increasing BMR. DIO rodent models: T3 supplementation reduces body weight, adiposity, and improves insulin sensitivity. Reference compound for thyroid-axis metabolic research.
Thyroid Receptor Pharmacology
TRα1 and TRβ1 isoforms mediate distinct tissue effects (cardiac vs metabolic). T3 is the reference agonist for both isoforms. Used in TR selectivity assays, gene reporter assays, and tissue-specific thyroid hormone signalling research.
Cardiac Research
T3 regulates cardiac contractility via myosin heavy chain isoform switching (MHC-α vs MHC-β), SERCA2a expression, and heart rate. Cardiac hypothyroidism models: T3 replacement restores contractility. Also studied in heart failure (post-cardiac surgery hypothyroidism).
Cholesterol / Lipid Metabolism
TRβ agonism in liver mediates LDL receptor upregulation and reverse cholesterol transport. T3 reduces LDL-C — mechanism behind thyroid-selective agonist drug development. Reference compound for understanding thyroid-lipid axis.
Key Research Data
Study
Key Findings
Nesto et al. Cardiac hypothyroidism
T3 replacement in post-bypass hypothyroidism: improved cardiac contractility, CO normalisation
DIO mouse metabolic models
T3 supplementation: reduced adiposity, improved GTT, elevated BMR vs vehicle
TR isoform selectivity assays
T3 reference agonist: TRα1 Ki ~0.1 nM, TRβ1 Ki ~0.1 nM — baseline for selective TR agonist comparison
Specifications
Format
Oral tablet — 25mcg per tablet
Purity
≥99% HPLC
Identity
MS confirmed
Storage
Room temperature, protect from light
vs T4
Direct thyroid receptor agonist — no conversion required; faster onset, shorter half-life than T4
FAQ
What is T3 (Liothyronine)?
T3 (Liothyronine) is a Thyroid hormone — active T3 form. Liothyronine (T3) is the biologically active thyroid hormone. Binds thyroid hormone receptors (TRα, TRβ) in the nucleus, directly modulating gene transcription. Controls basal metabolic rate (BMR), thermogenesis, cardiac output, protein synthesis, and choleste…
What research applications does T3 support?
T3 directly upregulates Na⁺/K⁺-ATPase, uncoupling protein (UCP), and mitochondrial biogenesis genes — increasing BMR. DIO rodent models: T3 supplementation reduces body weight, adiposity, and improves insulin sensitivity. Reference compound for thyroid-axis metabolic research….
How does T3 compare to similar compounds?
TRα1 and TRβ1 isoforms mediate distinct tissue effects (cardiac vs metabolic). T3 is the reference agonist for both isoforms. Used in TR selectivity assays, gene reporter assays, and tissue-specific thyroid hormone signalling research….
Does QSC ship T3 to the USA?
Yes. QSC ships domestically across the USA and to EU, UK, Canada, and Australia. Every batch carries a Janoshik third-party COA confirming ≥99% HPLC purity and MS identity.
