Thyroid gland

My daughter is 7 years old. Like other children her thyroid glands are not properly placed and the only tissue that works as the gland can be seen protruding like an adams apple in men. We diagnosed this is because of the tissue doing more work and that it needs a supplement. That is how we landed in her taking eltroxin. Once she started taking supplement through eltroxin the protruding tissue slowly subsided and the neck looks normal. We have confirmed also through needle test that is no other tissue and that it is the only working thyroid tissue. What I would like to know is. 1. Since the supplement is life time, will there be any side effects in the later stage? 2. Do I have to go through a needle test every year to check the tissue? 3. Is there any other remedies for thyroid supplement?