Raw research findings for this medication. Mostly single studies, not curated or confirmed robust.
Liothyronine is a manufactured form of T3 (triiodothyronine), the active thyroid hormone. It acts faster and for a shorter time than levothyroxine (T4). It is used for some cases of underactive thyroid, in thyroid cancer care, for myxoedema coma, and sometimes as an add-on in depression. It is sold as Cytomel, among other names.
Liothyronine is broken down by deiodinase enzymes. The single gene study listed, from a study of depression treatment, looked at the serotonin receptor gene HTR1B. Studies of the deiodinase gene DIO2 have also been discussed in relation to how people feel on levothyroxine alone, with mixed results. There is no CPIC or DPWG guideline.
Every published finding on gene variants and Liothyronine. Upload your DNA file to see which of these rows apply to you.
PharmGKB weighs all studies of a variant and rates how strong the evidence is, from 1A (strongest) to 4.
HTR1B rs130058: Level 3. Toxicity: Depression. 1.
Study findings and evidence levels: PharmGKB (CC BY-SA 4.0). Guidelines: CPIC and DPWG, as bundled in PharmCAT. Most studies were done mainly in people of European ancestry.
More drugs from the same category
Antithyroid Drugs (class) (Antithyroid Agents)
Not a prescribing recommendation. This page is educational information about pharmacogenomic research and clinical guidelines - it is not medical or dosing advice, and not a prediction of how any medication will work for you. Never start, stop, or change a medication or dose based on it; talk to your doctor or pharmacist, who can order clinical-grade testing if appropriate.
Content updated September 2026.
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