This is a pretty good article about the thyroid and what happens in hypothyroidism...here's the link:

http://www.healthy.net/scr/article.aspx?Id=528

Note the part about the thyroid getting locked into a negative state in times of stress---sound familiar to anyone?----here's that part:

"However, this response appears to occur to a wide variety of stressors and sometimes this mode is not reversed, even after the stress is removed. This can lead to all of the symptoms and signs of a low thyroid that I have been discussing." (this is at the bottom of page 4 of the article).

So, one may actually have low production of T3 and/or T4, but also may have low T3 and/or T3 because of problems converting T4 to T3, in which case blood tests can show up as normal, but the body is hypothyroid nonetheless. The good news, as I read the article, is that one can "reset" the thyroid with thyroid drugs, assuming all the thyroid nutrient requirements are met...which leads me to another question:

how many here take mineral supplements besides a vitamin/multivitamin
supplement? Most vitamin supplements don't contain minerals, and if they do, the ones I have found don't have the minerals in the right combination and/or form. Minerals appear critical to a healthy thyroid, particularly selenium, magnesium, iodine, copper.