Last reviewed · How we verify

Levothyroxin-Na

Sanofi · FDA-approved active Small molecule

Levothyroxine sodium is a synthetic thyroid hormone that replaces or supplements endogenous thyroid hormone to restore normal metabolic function.

Levothyroxine sodium is a synthetic thyroid hormone that replaces or supplements endogenous thyroid hormone to restore normal metabolic function. Used for Hypothyroidism, Thyroid cancer suppression therapy, Myxedema coma.

At a glance

Generic nameLevothyroxin-Na
SponsorSanofi
Drug classThyroid hormone replacement
TargetThyroid hormone receptors (TR-alpha and TR-beta)
ModalitySmall molecule
Therapeutic areaEndocrinology
PhaseFDA-approved

Mechanism of action

Levothyroxine (T4) is converted peripherally to the active form triiodothyronine (T3), which binds to thyroid hormone receptors in target tissues to regulate metabolism, growth, and development. It is used to treat hypothyroidism by restoring adequate circulating thyroid hormone levels and normalizing TSH feedback. The drug increases metabolic rate and energy expenditure across multiple organ systems.

Approved indications

Common side effects

Key clinical trials

Primary sources

Every claim on this page is sourced from regulatory or scientific primary sources. See our editorial policy for full methodology.

SourceUsed for
ClinicalTrials.govTrial enrolment, design, endpoints, results