Thanks for the reply.
The antibody levels are not high - 18.7 - but when they have been undetectable for 7-8 years, it is not the norm for me :-).
They are not sure either - obviously something is causing my body to make them. Was wondering if they a could be 'attracted' to parathyroid glands as I still have those. I have an ultrasound booked in as there is a small swelling around the neck area.
We talked about the thyroglobulin level still being good - but she said that as the antibodies are present that it makes this reading unreliable.
Will post when I hear/find out more.