3,5,3S-triiodothyronine

3,5,3′-tri·i·o·do·thy·ro·nine

(-trī′ī-ō′dō-thī′rə-nēn′, -nĭn)
n. Abbr. T-3
A thyroid hormone found in plasma and the thyroid gland that is similar to thyroxine in biological action, used in the treatment of hypothyroidism.