Thread: Thyroid Hormones 101
09-08-2001, 10:43 PM #1
Thyroid Hormones 101
Thyroid hormones are derivatives of tyrosine (an amino acid) bonded covalently to iodine. The principal thyroid hormones are thyroxine (also called T4) and triiodotyronine (also called T3). These hormones are essential formed by the linking together of two tyrosine molecules with the addition of three or four iodine atoms covalently bonded to the aromatic rings of these structures. The number of iodine atoms as well as their positions are extremely important as they ultimately determine the nature of the resulting molecule. That is to say that there are a few such iodinated molecules formed that have no biological activitty whatsoever, such as reverse T3.
The thyroid gland secretes mostly T4, however T3 is a much more potent and biologically active hormone. Some T3 is also secreted but most of the T3 found in the blood is formed by the deiodination of T4, a process that mainly occurs in the liver and the kidneys. This process also often yields reverse T3.
Thyroid hormones are not very soluble in water and most T3 and T4 is bound to carrier proteins, most noteably thyroid-binding globulin, a glycoprotein. These carrier proteins allow there to be a stable amount of free, unbound thyroid hormones circulating in the blood to be uptaken by target cells by releasing the active hormones periodically.
The synthesis and secretion of thyroid hormones is regulated by thyroid-stimulating hormone (TSH). TSH is released from the anterior pituitary and travels to the thyroid gland where it binds to target cells.
It is very probable that all cells in the body are targets for thyroid hormones. So, it seems logical that these hormones should have many physiological effects, and they do. Probably among the most obvious effects is an increase in metabolic activity resulting in an increase in basal metabolic rate. A result of this is an increase in body temperature as many users of T3 have noted.
These hormones also impact growth. This is seen quite clearly in the growth retardation of children who are deficient in thyroid hormones. They can also increase protein synthesis to a degree.
Other effects of these hormones include the development of the brain during early stages of life, increased heart rate, increased vasolidation, effects on mental well-being, and infertility in peeps with hypothyroidism.
Alright, I'm tired and am going to leave it at that. Bump if you appreciate this type of post.
09-09-2001, 07:50 AM #2ptbyjason Guest
bump for Nathan and his new avatar
09-09-2001, 08:01 AM #3Senior Member
- Join Date
- Nov 2001
- Back from Hell
Nathan nice post
09-09-2001, 10:30 AM #4
09-09-2001, 05:16 PM #5
09-09-2001, 09:20 PM #6
Id like to hear more on that
09-10-2001, 12:05 AM #7CYCLEON Guest
nice info nathan - that should help some of the newbies around here for sure.
09-10-2001, 12:03 PM #8
Ill Bump that... Nice info specialy for us newbies thinking of stacking T3 in our next cycle.
07-08-2003, 12:29 AM #9AR-Hall of Famer / Retired
- Join Date
- Aug 2001
- Wherever necessary
Its amazing what nathan could actually post back when he was kissing butt to make mod - now he just kisses butts for the fun of it
07-08-2003, 12:35 AM #10
Bump for charachter good post!
07-08-2003, 08:16 AM #11Originally Posted by CYCLEON
07-08-2003, 10:05 AM #12
I'm naturally on T3. I have an over active pituitary & thyroid gland. That's why it's such a bitch for me to gain weight.
07-08-2003, 05:59 PM #13
12-14-2004, 10:49 PM #14Retired Vet
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- Feb 2004
12-15-2004, 12:29 AM #15
12-15-2004, 12:46 AM #16
wow this is really old!
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