Of what importance is T4 and T3 in the case of a underactive thyroid

[bigfatmom]

Hi

I was recenlty diagnosed with a underactive thyroid and am now on 75mcg thyroxine.

I have regular blood tests to check my TSH but I have heard T4, and T3, mentioned alot but I am confused as to what this means.

Can anybody explain it to me.
My T4 and T3 has never been mentioned by the doctor and not sure if that is been checked as well.

Is this something that should also be checked and I need to ask about.

TSH is thyroid stimulating hormone. This is made by your piturity gland (haven't spelt that right) and tells your thyroid how much thyroid hormone to make. If it is a higher or lower amount than normal it means your system is out of whack and your body's trying to compensate. T4 and T3 are two of the thyroid hormones that the thyroid makes in response to this.
I believe that most labs test for the TSH in your blood first and if this is within 'normal range' they don't bother testing for T3 and T4.
Hope this helps? Otherwise there are some good websites if you do a google search. An excellent book is "the healthy thyroid" by Patsy Westcott.
Hope you are feeling better since starting treatment - can take a while sometimes. I'm overactive myself and was amazed to discover the impact this little gland has on your body (and life)!