“Your thyroid gland, as an endocrine gland, makes and secretes hormones. Your thyroid produces and releases the following hormones:

• Thyroxine (T4): This is the primary hormone your thyroid makes and releases. Although your thyroid makes the most of this hormone, it doesn’t have much of an effect on your metabolism. Once your thyroid releases T4 into your bloodstream, it can convert to T3 through a process called deiodination in the liver.
• Triiodothyronine (T3): Your thyroid produces lesser amounts of T3 than T4, but it has a much greater effect on your metabolism than T4.
• Reverse triiodothyronine (RT3): Your thyroid makes very small amounts of RT3, which reverses the effects of T3.
• Calcitonin: This hormone helps regulate the amount of calcium in your blood. It plays a role in regulating the level of calcium in your blood by decreasing it. The C-cells in your thyroid gland produce calcitonin.

Your thyroid’s main job is to control your metabolism — how your body uses energy. Sometimes, your thyroid doesn’t work properly. These conditions are common and treatable.

More than 12 percent of the U.S. population will experience a thyroid condition at some point in their lives.  Yet, thyroid disease often goes undetected: as many as 60% of people don’t know they have it, which is why regular screening is important.”

Cleveland Clinic (https://my.clevelandclinic.org/health/body/23188-thyroid)