Levothroid Uses

Levothroid Uses for Other Thyroid Problems

The amount of thyroid hormones produced by the thyroid gland is controlled by another hormone, called thyroid-stimulating hormone (TSH). TSH is produced in the pituitary gland. If your thyroid hormones are low, TSH increases in order to stimulate your thyroid to make more hormones. If your thyroid hormones are high, TSH is low, signaling the thyroid to make fewer hormones. An easy way to remember this is to note that TSH and thyroid hormone levels are usually opposite; if TSH is high, then thyroid hormones are usually low (and vice versa).
High TSH can stimulate the growth of goiters and some thyroid cancers. Therefore, giving extra thyroid hormone (in the form of Levothroid) will decrease TSH, which can help to shrink goiters and some thyroid cancers.

How Does Levothroid Work?

The thyroid gland makes two different thyroid hormones, levothyroxine (T4) and triiodothyronine (T3). Typically, the thyroid produces much more T4 than T3 (however, T3 is much more active than T4). The body can convert the T4 hormone into T3 as necessary. If your thyroid does not make enough thyroid hormones, there are a few different ways to increase your levels.
Some forms of thyroid replacement combine T4 and T3 (such as natural thyroid replacement made from pig thyroids). However, because the body converts T4 into T3 as needed, most people can successfully take just T4 (such as Levothroid). Alternatively, just T3 can be taken (such as Cytomel®). Currently, most people just take T4.
Contrary to what you might find stated on the Internet, Levothroid was approved by the U.S. Food and Drug Administration (FDA) in 2002, while natural thyroid products (such as Armour® Thyroid or Nature-Throid™) are not FDA approved. Natural thyroid products were on the market long before the FDA existed, and the makers of these products have not chosen to seek FDA approval for their products.
Last reviewed by: Kristi Monson, PharmD
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