Synthroid is a manufactured, artificial form of the thyroid hormone, thyroxin. It is primarily used to treat thyroid hormone deficiencies including the form known as myxedema coma.
This medication is also often used to treat various types of thyroid disorders such as multiple forms of goiters, thyroid tumors, cancers, and diseases which are caused by hormone imbalances in the thyroid gland.
The active ingredient in Synthroid is levothyroxine sodium, coupled with inactive ingredients such as lactose, magnesium stearate, and povidone, etc. It is also often used to suppress TSH levels as well.