Hypothyroid lab results

My doctor discovered a slightly high (5.1) TSH reading for me in July of 2008, so she suggested I go on Synthroid 50 mcg.  After 6 weeks my TSH reading was 6.2, so she put me on 75 mcg.  My T4 is 10.1.  I am experiencing some side effects from the Synthroid, mainly joint aches.  My question is:  why did my TSH go up if I was on Synthroid, even if the dose isn't enough?  Thanks.

[ChitChatNine]

Did they do antibody tests?  Welcome to the community!

C~

[Tracy926]

Thanks for the welcome!  Yes, the antibody tests were done the first of August, and came back at 4500.  I'm having another blood test this morning to see if my TSH has gone down.  I asked my doctor yesterday if she could explain why my TSH went up after starting on 50 mcg of Synthroid, and she said maybe we were at the cusp of the disease, and it would have gone up more if I hadn't been on the 50 mcg.  I guess that could be, although it seems pretty coincidental.