Liothyronine (T3)
li-oh-THYE-ruh-nine
Category
Compound type
Phase / Status
FDA approved for hypothyroidism
Standard Dose
As directed
Half-life
Plasma elimination
Route(s)
Oral, Injectable or Topical
Research Stage
Regulatory approval granted; post-market monitoring ongoing.
Overview
Liothyronine is T3 - the active thyroid hormone that helps set how quickly many body systems run. If T3 levels are too high or too low, people can notice symptoms across the body, including heart-related effects. Using thyroid hormones outside an individualized prescription plan is risky, and it's not the kind of compound to treat like a supplement. If someone is considering T3, the safer path is to talk with a clinician and use appropriate thyroid lab monitoring.
Plain-language summary
Liothyronine is T3 - the active thyroid hormone that helps set how quickly many body systems run. If T3 levels are too high or too low, people can notice symptoms across the body, including heart-related effects. Using thyroid hormones outside an individualized prescription plan is risky, and it's not the kind of compound to treat like a supplement. If someone is considering T3, the safer path is to talk with a clinician and use appropriate thyroid lab monitoring.
Administration Routes
- Oral
- Injectable
- Topical
Also known as
Mechanisms
Synthetic T3 (triiodothyronine) thyroid hormone
Detailed mechanism
Liothyronine (T3) is the biologically active form of thyroid hormone that enters cells via monocarboxylate transporter 8 (MCT8) and binds nuclear thyroid hormone receptors (TR-alpha and TR-beta), which act as ligand-activated transcription factors regulating genes involved in basal metabolic rate, thermogenesis, protein synthesis, and lipid oxidation. T3-receptor complexes upregulate uncoupling proteins (UCP1/2/3) in mitochondria and increase Na+/K+-ATPase activity, raising cellular oxygen consumption and heat production - the mechanism underlying T3's use as a metabolic accelerant in competitive physique preparation. Because exogenous T3 suppresses TSH via pituitary negative feedback, abrupt discontinuation can cause transient hypothyroidism as the HPT axis resets, necessitating gradual dose tapering when ending a cycle.
Safety
Side effects
- Tachycardia
- Anxiety
- Muscle loss
- Cardiac stress
Reported benefits
- Increased metabolism
- Fat loss
- Energy boost
Safety profile
Consult medical professional before use
Clinical trials
See research status
Structure
Verified structure
Liothyronine (T3)
Exact 2D structure can be rendered from a PubChem-backed canonical SMILES string.
- Chemical Formula
- C15H12I3NO4
- Molecular Weight
- 650.97 g/mol
- CAS Number
- 6893-02-3
- InChIKey
- AUYYCJSJGJYCDS-UHFFFAOYSA-N
Stack Context
No stack data available.
References
- 1View source
Liothyronine - PubChem Compound Summary (NLM)
- 2View source
Liothyronine Sodium Tablets - DailyMed Prescribing Information (cardiac adverse reactions/atrial fibrillation risk)
- 3View source
Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force on Thyroid Hormone Replacement (Thyroid)
2014
- 4View source
Effects of thyroxine as compared with thyroxine plus triiodothyronine in patients with hypothyroidism (NEJM)
1999
This profile summarizes research literature for education only. It is not medical advice, and it does not diagnose, treat, or recommend a dose. Consult a qualified professional before changing a protocol.