Levothyroxine (T4)

Overview

L-thyroxine is the L-enantiomer of thyroxine. It has a role as an antithyroid drug, a thyroid hormone, a mouse metabolite and a human metabolite. It is an iodophenol, a thyroxine, a 2-halophenol, a non-proteinogenic L-alpha-amino acid and a L-phenylalanine derivative. It is a conjugate acid of a L-thyroxine(1-). It is an enantiomer of a D-thyroxine. It is a tautomer of a L-thyroxine zwitterion.

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

PubChem record

CID 5819 · Thyroxine

Molecular formula · weight

C15H11I4NO4 · 776.87 g/mol

PubMed papers naming it (title/abstract)

6,673 search: “Levothyroxine”

Registered clinical studies (ClinicalTrials.gov)

342 intervention: “Levothyroxine”

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