Levothyroxine
SynthroidPubChem CID 5819 · 3D model
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Supplies the body with a lab-made copy of its own thyroid hormone, restoring the chemical signal that keeps metabolism running at a normal pace.
How it works
Levothyroxine is a synthetic, exact copy of the main hormone your thyroid gland normally produces. Once in the body, most of it is converted into a more active form that enters the control center of cells and switches on the genes responsible for metabolism — things like energy use, body temperature, heart rate, and growth. By replacing the hormone a person's thyroid isn't making enough of, it brings those processes back to a normal pace. At higher doses, it also signals the pituitary gland to stop overproducing thyroid-stimulating hormone, which is how it's used as part of thyroid cancer treatment.
What it’s used for
Used to treat an underactive thyroid in adults, children, and newborns by replacing the hormone the thyroid isn't producing enough of. Also used alongside surgery and radioactive iodine treatment to help manage certain thyroid cancers, by keeping thyroid-stimulating hormone levels low. It is not used for simple thyroid nodules or a mildly enlarged thyroid in people whose thyroid function is otherwise normal.
- Mechanism
- Thyroid hormone receptor agonist
- Drug class
- Small molecule
- Therapeutic area
- Endocrine