I recently tested as a 5.1 on my thyroid blood test. My doctor said that he wants to keep an eye on it and if my numbers go up, he is going to put me on medication. I have been having break through bleeding, which recently just started, and my periods have been lighter. I am on the pill and have been for about 4 years now. I never had a problem with my cycle before and am getting concerned. I was wondering if a reading of 5.1 for my thyroid could be causing the problem?