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Old Thu, Mar-10-05, 13:54
Natrushka Natrushka is offline
Senior Member
Posts: 11,512
 
Plan: IF +LC
Stats: 287/165/165 Female 66"
BF:
Progress: 100%
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Quote:
Most doctors will only prescribe synthetic T4. Why, you ask, when the active form of thyroid hormone is T3, do they prescribe T4? T4 is what you can think of as being the "battery" form thyroid hormone. The thyroid gland and liver are capable of changing T4 into T3 as needed. T4 on its own might not really do anything (I'm not sure about that) except circulate around in your blood stream until you need it.[/url] Then the T4 is converted to T3 and bingo, you've got fuel for your metabolism.


There are some errors in here, Nancy. The thyroid produces T3, it does not turn T4 into T3. That happens in the liver, yes, and peripherally - in other tissue. The most important place it happens is in the brain. Which is why the statement in red is off; T3 cannot cross the blood brain barrier, you need T4 in the cerebellum and cerebral cortext to convert into T3. Some folks to very well on only T4, but they are in the minority. Just as only T3 treatment is not optimal, neither is T4. You need both, or the thyroid wouln't bother making both.
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