Wow - what a coincidence that this thread has popped up. I am going through all this atm. I have had all the tests, including that horrible test where you are injected witjh radioactive stuff. Turns out that there is a small chance that I may have thyroid cancer. I see the specialist on Friday and I also am having a fine needle aspiration.
So thanks to all that have added posts about the function of the thyroid. It has helped me heaps.