Liothyronine (T3)

Overview

3,3',5-triiodo-L-thyronine is an iodothyronine compound having iodo substituents at the 3-, 3'- and 5-positions. Although some is produced in the thyroid, most of the 3,3',5-triiodo-L-thyronine in the body is generated by mono-deiodination of L-thyroxine in the peripheral tissues. Its metabolic activity is about 3 to 5 times that of L-thyroxine. It has a role as a thyroid hormone, a mouse metabolite and a human metabolite. It is an iodophenol, an iodothyronine and a 2-halophenol. It is a conjugate acid of a 3,3',5-triiodo-L-thyroninate. It is a tautomer of a 3,3',5-triiodo-L-thyronine zwitterion.

Source: ChEBI (CC BY 4.0), via PubChem.

PubChem record

CID 5920 · Liothyronine

Molecular formula · weight

C15H12I3NO4 · 650.97 g/mol

PubMed papers naming it (title/abstract)

478 search: “Liothyronine”

Registered clinical studies (ClinicalTrials.gov)

907 intervention: “Liothyronine”

Reference facts checked 2026-11-09. Counts are search results, not a judgement of the evidence.