Yes, I've taken guggul. I didn't notice any dramatic effects but may not have taken it long enough; and I certainly felt fine when I was taking it. I've used Himalayan Herbal Health brand for that and some other remedies, it seems to be of very good quality and there's a lot of info about the remedies on their site.

I have read that guggul is sometimes best taken in combination with other herbs to increase its effect.

I haven't had the tests you refer to but my mother has had a long-standing thyroid deficiency so I've wondered if mine might be affected too. I especially noticed problems in November/December when the cold and darkness set in. At that point I bought some kelp (the pieces, not flakes) and toasted them, I felt so much better. High in iodine and other minerals. (I've never felt great using the seaweed flakes or powders but some people are OK with them.)

There's a good article on the thyroid imbalance and alternative remedies by Susun Weed that you may be able to find online, I'll see if I can dig it up.

Added: can't 'find that article online anymore but there's a good chapter on thyroid health in her Menopause book. I did locate an article on seaweeds: http://www.susunweed.com/Article_Seaweed.htm