[Anonymous]

#1046541

Hi, Vi and Sally!

The best place to find a terminology index is to order thyroid-related books from your local bookstore or online at amazon.com. The NGDF will receive a portion of the proceeds, if you order from amazon via our website at http://www.ngdf.org. Thanks for your support!
I recommend these books:

“The Thyroid SourceBook: Everything You Need to Know”
M. Sara Rosenthal
Lowell House / August 1996

“Your Thyroid, A Home Reference”
Drs. Wood, Cooper, Ridgway
Ballantine Books / July 1996

Instead of me trying to explain T3 and T4, I will refer you to an old post from Bobbi that will hopefully answer all of your questions. She’s much better at that technical stuff than I am.

Wishing you good health and happiness,
Debby
OLAF, NGDF

T4/T3/Replacement treatment
Posted by : Bobbi on August 3, 1997 07:33:57

Here is the short-course (amateur style) on these hormones.

The thyroid produces two main hormones, identified by the number of iodine atoms in them as T4 and T3, in a proportion of approximately 4:1. The T3 hormone is the one that the cells use for metabolism. There are a variety of places in the body (the liver and kidneys being two of the major ones), where the T4 is naturally converted to T3 after leaving the thyroid, as the body needs it.

When it comes to thyroid replacement hormone treatment, the standard
treatment is to give only T4. Why? Well, first there’s the fact that the
body naturally converts it to T3 as needed. Secondly, T3 is monumentally
more potent than T4 AND has a very short life span, so it is much more
difficult to regulate the dosage, and there are more potential negative side effects. (Specifically, T4’s half-life in the body is 6.7 days, whereas T3’s half life is 0.75 days.) There are some folks for which the standard T4 treatment does not seem to work well, for whatever reason, so there are a variety of thyroid hormone replacement products available for the doctors to prescribe.

The first hormone replacement products were, and still are, made from
grinding up pork and beef thyroids. These include Armour Thyroid, Thyroid Strong, Thyrar, and SPT. According to The Pill Book “These were effective but lacked standardization, which made it difficult for some doctors to control their patients’ thyroid condition.”

Then, the man-made (synthetic) hormones were developed. They are chemically identical to the naturally occurring hormones. It is much easier to standardize the dose contained in each pill, so doctors have begun to prescribe them the most.

The T4 replacement hormone (levothyroxine sodium) is available under the
brand names Levothyroid, Levoxyl, Synthroid, and Levoxine.

Cytomel is straight T3 (generic name liothyronine sodium) . It is possible, although difficult I understand, to get a time-release form of cytomel as well.

There is a combination T4/T3 product (generic name liotrix) available under the brand names Euthroid and Thyrolar. This contains the 4:1, naturally occurring proportions of the hormones.

I hope this helps.

Bobbi

[Author]

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