Hm. Just thought that I'd post this here, as I am pretty sure that I'm not the only one of us who has to take thyroxin due to lack of part / all of the thyroid gland...
Basically I recently had a small argument with the vacation stand-in for my normal doctor, as she was telling me that my TSH value of 1.7 was fine, which wasn't quite the case due to my history (hospital said to keep it between 0.5 and 1.5 max, and I've been running at about 1 for 6+ years now

). She agreed in the end, but only after reading through the documentation. As I tend to over-prepare myself for stuff like that, I did a little research, and stumbled across the following somewhat interesting publication:
QuoteArafah, B. (2001) 'Increased need for thyroxine in women with hypothyroidism during estrogen therapy', The New England Journal Of Medicine, 344(23), pp.1743-1749.
http://www.ncbi.nlm.nih.gov/pubmed/11396440
Essentially what Arafah found is that the oestrogen therapy can result in a higher level of thyroxin-binding globulin etc. So what this means is that us ladies that are taking thyroxin should keep a very close watch on their TSH levels, as our dosage may require a slight upward adjustment. Just one of those things in our particular situation.