A lot of my hair has also fallen out. I have always had thin/hair but in the past 4 1/2 months since I've had mirena out, I have lost quite a bit. Around my hairline on my forehead is extremely bad. I look like a 40 year old man with a receeding hairline and right about my ears is really thin. It is getting to the point where it is very noticable whether I wear my hair up or down. I too thought I had an overactive thyroid but apon testing was told that and my other hormone levels were "normal". BUt I know that is what it is from, since this never happened before the mirena. Sorry to hear you are going through this because I know how bad it is and dont wish this on anyone. I hope you and I both will begin to get better.