Blog — Thyroid Hormone Bioavailability

The thyroid is a small butterfly-shaped gland located in the front of the neck, just below the Adam's apple. It plays a crucial role in regulating various bodily functions by producing hormones that control metabolism and energy production. Thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3), influence the functioning of almost every organ in the body, including the heart, brain, muscles, and skin.The thyroid gland functions under the control of the hypothalamus and the pituitary gland. The hypothalamus releases thyrotropin-releasing hormone (TRH), which signals the pituitary gland to release thyroid-stimulating hormone (TSH). TSH then stimulates the thyroid gland to produce...

Part 1 By Margaret Groves, ZRT Laboratory Thyroid hormones are essential for the normal metabolic functioning of all tissues in the body, and a wide array of symptoms are therefore associated with abnormalities in thyroid hormone production and activation. Even when apparently adequate amounts of thyroxine are produced by the thyroid gland, thyroid function is profoundly affected by anything that disrupts conversion of thyroxine (T4) to the active thyroid hormone, triiodothyronine (T3). This conversion takes place primarily at the cellular level within tissues; only 20% of circulating T3 is generated by conversion of T4 within the thyroid gland itself. The deiodinases...