The number after the «T», such as T3 or T4, stands for the number of iodine molecules the hormone contains. (articles.mercola.com)
Following their first steps using the relatively simple iodine molecule, the team is now planning to expand their studies to molecules with more than two atoms. (sciencedaily.com)
It's because we're pulling 1 iodine molecule off it. (justinhealth.com)