Hello – Hopefully, you will get some other responses, but this is a nice piece that discussed possible reasons for persistently elevated TSH:
(Note on links: if you click directly on the following link, you will need to use your browser’s “back” button to return to the boards after viewing, or you will have to log back in to the forum. As an alternative, you can right-click the link and open it in a new tab or new window).
http://www.medscape.com/viewarticle/705879
I am registered on the medscape page, so you might need to do an individual registration (which is free) to view the article.
You didn’t mention whether or not you were eating large amounts of soy or taking supplements (iron, calcium) that might interfere with absorption. That would be one issue to take a look at before looking for other causes.
Hope you can get some relief!