Thyroxine is the principal hormone produced by the thyroid gland. It promotes protein synthesis (blending) and growth, and also helps regulate the body's metabolism.

Thyroid Stimulating Hormones

Thyroxine is produced by the thyroid gland in a very complex way. When the blood's thyroxine level is low, the brain's hypothalamus (the part of the brain that regulates body functions) produces a thyrotropin-releasing hormone. This stimulates the pituitary gland to produce thyrotropin. Thyrotropin is a thyroid-stimulating hormone (TSH) that excites the thyroid gland. When the blood's thyroxine level is high, the hypothalamus releases a hormone that inhibits TSH production.


Hyperthyroidism is a condition caused by an overactive thyroid. The syndrome can cause weight loss, nervousness, and protruding eyes. Called Graves's disease, it was first identified by Irish physician Robert James Graves (1796-1853).

Treating Underactive Glands

German chemist Eugen Baumann (1846-1896) was the first researcher to treat underactive thyroids using extracts made from animal thyroid glands. In 1914 American biochemist Edward Kendall isolated and used the crystalline form of the hormone which was later named thyroxine. In 1926 the British chemist C. R. Harington (1897-1972) determined thyroxine's exact structure and synthesized it out of materials in a laboratory.

Treating Overactive Glands

Today, overactive glands can be treated with medication, removed surgically, or destroyed by radiation. When the gland is removed or destroyed the patient must always take thyroid hormones as replacement therapy. Hormone therapy is also used for underactive glands.

The first widely-used test to measure peoples' thyroid levels was developed in the 1930s by American biochemist Evelyn B. Man (1904-1992). Called the protein-bound iodine test, it soon showed that many "demented" patients in mental hospitals (those having deteriorated mental capabilities) actually had underactive thyroid glands. Treatments with thyroxine helped many of these patients regain normal mental abilities.

Doctors now routinely evaluate an infants' thyroid function by testing blood from newborn babies' umbilical cords. This allows correction of any thyroid gland problem before mental or physical damage occurs.

User Contributions:

Report this comment as inappropriate
Oct 1, 2010 @ 9:21 pm
My T3 and T4 are in good range. The problem is that a year ago I had a TSH of 3.80 This year my TSH is .03 I am constantly gaining weight would this because of the pituitary. I have had an ultrasound of my thyroid and they have found nodes on my thyroid. I also had a traumatic brain injure in a car accident and wonder if that could have damaged the pituitary. My doctor wants me to go to another endocrinologist what can I ask and expect he will look for?
Report this comment as inappropriate
Apr 22, 2011 @ 1:13 pm
well my TSH rate is 24.00 and dr. prescribed me thyroxine is it rite for me..??
Report this comment as inappropriate
May 5, 2011 @ 8:08 am
Report this comment as inappropriate
Dec 2, 2011 @ 4:04 am
I wan't to tell me the effects and benifit of tri-iodothymine and thyroxine
Report this comment as inappropriate
Aug 1, 2014 @ 12:00 am
Bright fashion is back again with a reiasprl: Brights can be smashed in red, fuchsia, pink, green, and orange. The vivid nails fashion can be coordinated to the lipstick fashion tendencies or outfits fashion and develop into an eye catchy accent in a neutral-based fashion search. Most recent nail fashion shades 2012 are just best if you want to go vivid all the way: Surpriseing fashion tendencies. This vivid red nail color fashion is inevitable for those who want each eye in the area to be drained to their nails. Sunshine Kissed fashion tendencies: Set on several coats of this great-searching yellow color, include a tap of gloss and include your eyes with Rimmel London Scandal eyes fashion mascara and you are all put to go in accordance to newest fashion tendencies 2012. Rara, is that strange fashion color that you consideration was only for night time-time functions, but it really being found all through the day. At fashion weeks and perhaps on the fashion streets of New York, the circulation of fashion this spring is to go a minor darker, a minor stranger and a minor much more theatrical all through the day. Rara is for all those who want to stand out for fashion and newest tendencies in this spring 2012.

Comment about this article, ask questions, or add new information about this topic:


Thyroxine forum