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T3, T4, TSH :s

Can someone please educate me better on T3, T4, and TSH.

I'll take a shot at it and you correct me. The thyroid gland produces T4 and the TSH converts it to T3. T3 is what you need to keep your body chemistry balanced.

If that part is right, where does the TSH come from?
Why is less TSH better than more?
How come the doctors don't give you T3?
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314892 tn?1264623903
TSH is Thyroid Stimulating Hormone. It is secreted by the pituitary gland to tell the thyroid how much thyroid horime to make.
The thyroid sends out t4 (which is what synthetic t4 meds imitate) and a majority of it is converted in the tissues to t3, which is the most active form of the hormone.
Giving t3 is not usually necessary unless a person had a conversion problem. This is apparently preyy rare. Most people will be able to convert t4 into t3.
The higher the TSH, the harder your pituitary is working to tell the thyroid to produce more t4. It also causes your thyroid to work harder trying to make the t4.
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Avatar universal
Wow, thx kitty! You explained it well.
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314892 tn?1264623903
You're welcome and thanks! (I work in the lab :)

Kitty
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Avatar universal
My as my tsh comes down my t4 goes up. What is this?
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314892 tn?1264623903
Hi.

The TSH and free t4 have an inverse relationship.
TSH goes higher when the free t4 is low to try to get the thyroid to produce more T4. When the TSH drops, the free t4 will increase.
You want a lower TSH and a free t4 in the mid to upper end of the range for optimal thyroid function. This should be the goal combined with how you feel at a certain level. You don't want the TSH to drop too low, which could push the t4 too high.

Hope this is clear enough.

Kitty
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Avatar universal
What does it mean if the TSH is high - ie 12 and the T4 is in the high range too - ie 12? Does this mean that the body is having difficulty converting the T4 to 3??
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Avatar universal
thanks that helps I am trying to get my synthrroid dose right. I went from 50 to 75 to too hyper back to to low now with my numbers I think I am just in between 50 and 75 somehow.
thanks again.
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314892 tn?1264623903
loissy- Here is a chart explaining the relationships between the various thyroid tests and their meaning. It does not mention your situation, though. What is the reference range for t4? Is it a free t4 or total? I don't know what it means in terms of conversion.

hitoyouto- Glad you are on your way to figuring it out!

Kitty
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