Thyroid hormone problems are closely linked with ovarian hormones. For many women, starting HRT is the final blow that pushes their thyroid hormones down to symptomatic levels. We've mentioned in the discussion of estrogen that it stimulates higher levels of a protein that binds (inactivates) thyroid hormone and in discussing progesterone that it affects levels of minerals necessary to use thyroid hormone inside the cell. Because of these interrelationships, it's wise to ask for thyroid testing if you are having difficulty with your balance, having some question as to whether what you are experiencing is due to ovarian or thyroid imbalance, or you have a pre-existing thyroid problem or a family history that leads you to suspect you might be at risk to develop one.
Many women feel unjustly picked-upon by discovering that, just as they're trying to sort out having one system go manual (ovarian hormones), suddenly their thyroid packs it in as well. Did their hyst cause this? No, not really. In fact, a lot of women in natural menopause experience the exact same thing and feel just as unfortunate. Menopause just seems to be the time when our thyroids are wearing down and can't cope with the additional burdens placed on them.
We won't go into a lot more detail here, but will instead refer you to the authoritative thyroid.about.com for a full discussion of diagnosis, testing, and treatment options. We will throw in the note that women with a badly out-of-balance thyroid are not likely to be able to balance their ovarian hormones until the thyroid hormones are closer to normal. This means that you may have to treat them sequentially, and in successive small iterations. This can be a long and even more frustrating process than balancing the ovarian hormones alone, and you have our sympathies.
One thing that is becoming clear as we see more women work the ovarian-thyroid connection is that women on a combination of T3 + T4 may do better than those on just synthetic T4 alone if they have trouble converting from one form to the other (this is common, apparently). In fact, this page goes into depth on the premise that people on a combination of the two claim they had "more energy, improved concentration, and just felt better overall" that those taking just T4. Once again, this takes us away from the simple answers to the complex and subjective, but if it's the route to feeling good, hey—we're for it.
For those who are using alternative HRT and hitting the soy heavily, you should know that soy may also interfere with thyroid function. We have actually seen women trying to use high soy intake to replace estrogen use drive their thyroid into depressed function from which it did not recover. That doesn't mean you have to avoid soy altogether, but it does mean that if you already have thyroid problems—or develop them—that soy may not be your best choice for alternative HRT.
One last note on necessary supplements: selenium is necessary to convert T4 to T3 (the active form). A lot of "silver" type multivitamins contain selenium. If yours doesn't, eating just two brazil nuts a day will meet your needs. Now, isn't that refreshingly simple?