What is the thyroid?
The thyroid is a small gland located in the front of the neck. It is made up of two halves, called lobes that lie along the windpipe (trachea) and are joined together by a narrow band of thyroid tissue.
Thyroid Hormone (TH) is produced by the thyroid gland in response to the release of thyroid stimulating hormone (TSH) from the pituitary gland. TH helps the body convert food into energy and heat, regulates body temperature, and impacts many other hormonal systems in the body.
Thyroid Hormone exists in two major forms:
- Thyroxine (T4), an inactive form that is produced exclusively by the thyroid gland.
- Triiodothyronine (T3), the active form of thyroid hormone. About 20 percent of T3 is produced by the thyroid gland, with the remainder produced through conversion of T4 in various tissues of the body when more T3 is needed.
Physicians note that despite apparently adequate replacement therapy with levothyroxine, some hypothyroid patients remain symptomatic. Studies suggest that replacement therapy for hypothyroidism with levothyroxine alone does not ensure normal thyroid hormone levels in all tissues, and that a combination of levothyroxine and T3 may be required for optimal thyroid replacement therapy. However, the only commercially available form of T3 for replacement therapy is synthetic liothyronine sodium, an immediate release formulation which is rapidly absorbed, may result in higher than normal T3 concentrations throughout the body, and may cause serious side effects, including heart palpitations.
Research indicates there is a need for sustained-release T3 preparations in order to avoid adverse cardiac effects due to high serum T3 levels which can result if the hormone is absorbed too rapidly.
A study published in the New England Journal of Medicine reported that treatment with T4 plus T3 improved the quality of life for most hypothyroid patients. The researchers also recommended that the ideal thyroid hormone replacement program for someone without a thyroid gland, or whose thyroid gland is nearly non-functioning, should include daily T3 in sustained-release form, along with enough T4 to ensure normal levels of thyroid hormone. Partial substitution of the T4 dose with T3 improved cognitive performance, mood, physical status, and neuropsychological function in hypothyroid patients.
For more information about thyroid hormone replacement using sustained-release T3 formulations, please contact one of our compounding pharmacists.