How does it work? The thyroid produces a hormone, thyroxine (or T4) that goes out to all our organs. Once it arrives at its destination organ, it's converted into another hormone, triiodothyronine (or T3). There, it sets the pace for your cells, helping them do what they're supposed to do. Basically, those hormones tell your heart to keep beating, your liver to keep metabolizing, and so on.