Notes

T4, formally known as Thyroxine, is one of the hormones secreted by the thyroid, and is important for ultimately controlling levels of stimulation of the thyroid. The thyroid is important for regulating the body’s muscular and digestive functions, brain and bone development, and most importantly, the body’s metabolic rate. Thyroxine is an essential hormone to development, and individuals with thyroid disorders struggle without its presence. Because of this, scientists have formulated a synthetic T4 with a long half-life that can be administered to individuals with hypothyroidism, a disease where individuals have low levels of thyroid hormones. These experiments gave hypothyroid patients a T4 monotherapy treatment at a singular dose and saw inconclusive evidence with some of their results. Ultimately, we are curious about how the body responds to T4 monotherapy treatment and discover when or at what dosage the treatment’s efficiency begins to decline.
Thyroxine’s production pathway begins at the hypothalamus. When stimulated, the hypothalamus releases thyrotropin releasing hormone (TRH). The TRH then binds to receptors on the anterior pituitary, stimulating the release of thyroid stimulating hormone (TSH). The TSH is required to produce any amount of thyroxine. This TSH then goes to the thyroid, binds to receptors, and stimulates the production of T3 and T4.
Thyroxine is regulated via a negative feedback loop. When there is adequate levels of thyroxine in the blood, the hypothalamus inhibits the release of the thyrotropin releasing hormone. This then inhibits the entire production pathway.
One aspect of hypothyroid research that has yet to be tested is the idea of varying doses of synthetic T4 in order to increase T4 and T3 concentrations within the body for a sustained period to increase the efficiency, efficacy, and sustainability of hypothyroid treatments.