How is T3 and T4 synthesized?
Through a reaction with the enzyme thyroperoxidase, iodine is bound to tyrosine residues in the thyroglobulin molecules to form monoiodotyrosine (MIT) and diiodotyrosine (DIT). Linking two moieties of DIT produces T4. Combining one particle of MIT and one particle of DIT produces T3.
Which hormone stimulates synthesis and release of T3 and T4?
TSH, in turn, stimulates thyroid follicular cells to release thyroxine or T4 (80%), and triiodothyronine or T3 (20%). Somatostatin, on the other hand, is another hormone produced by the hypothalamus that inhibits the release of TSH from the anterior pituitary.
What are the basic steps of thyroid hormone T3 T4 synthesis?
Thyroid hormone synthesis includes the following steps: (1) iodide (I-) trapped by the thyroid follicular cells; (2) diffusion of iodide to the apex of the cells; (3) transport of iodide into the colloid; (4) oxidation of inorganic iodide to iodine and incorporation of iodine into tyrosine residues within thyroglobulin …
Where is T3 and T4 secreted from?
The thyroid gland is essential to the endocrine system. It is located in front of the neck and is responsible for the production of thyroid hormones. The thyroid gland releases triiodothyronine (T3) and thyroxine (T4).
How is T 4 converted to T 3?
T 4 is then converted to either T 3 or rT 3 by the enzyme ‘Iodinase’ which is present throughout the body’s tissues. The thyroid gland is full of thyroid follicles which are the basic units of thyroid hormone synthesis (For detailed histology see Thyroid Histology ).
Which is more potent, T4 or T3?
T4 is deiodinated to T3, which is a more potent thyroid hormone. While about 20% of T3 originates from the thyroid gland, 80% of T3 is produced by peripheral conversion via a deiodinase especially type2. More than 99% of thyroid hormone is protein bound to thyroid binding globulin, pre-albumin, and albumin.
What happens when T4 is released into circulation?
When T4 is released into circulation, it can be converted to T3 through the process of deiodination. T4 and T3 can then exert negative feedback on TSH levels with high levels of T3/T4 decreasing TSH and low levels of T3/T4 increasing TSH levels from the anterior pituitary.
How are thyroid peroxidase and anti-Tg antibodies related?
The serum concentrations of anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) antibodies are directly correlate in the induction and diagnosis of autoimmune thyroid disorders (AITDs). Therefore, the evaluation of serum anti-TPO and anti-TG antibodies in relation to thyroid function …