1. Hyperthyroidism Slideshow Pictures
2. Take the Thyroid Disorder Quiz
3. Thyroid Symptoms and Solutions Slideshow Pictures

Medical Author:

Stephanie L Lee, MD, PhD, FACE

Coauthor:

Sonia Ananthakrishnan, MD

Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Levothyroxine (L-thyroxine)

The majority of people with hypothyroidism are treated with one of the synthetic forms of the T4 thyroid hormone (Levoxyl, Synthroid). This is a more stable form of thyroid hormone and requires once a day dosing, whereas preparations containing T3 (the most active thyroid hormone) are much shorter-acting and need to be taken multiple times a day. Synthetic T4 is readily and steadily converted to T3 naturally in the bloodstream in the great majority of people, and this conversion is appropriately regulated by the body's tissues. A brand name preparation of L-thyroxine is recommended over generic preparations, and individuals should use the same brand of levothyroxine throughout treatment (See Figure 1 below).

Figure 1: The "rainbow" of L-thyroxine dose pills available. For patients taking L-thyroxine, blood levels of TSH should be checked every four to six weeks, in order to see if a L-thyroxine dose change is necessary

Other thyroid hormone replacements are available but are not often recommended for replacement therapy. These include: desiccated thyroid hormone, T3 (triiodothyronine), and combinations of thyroid hormones T3 and T4.

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