If you have the autoimmune type of Thyroid Disease, it doesn't go away after the surgery, however Sarsar is right in that you have to be re-evaluated. My doctor told me that it is not uncommon to have to have a reduction in the dose following a large weight loss. I have not had my post op Thyroid evaluation yet as I am only 3 weeks out, but I will be going in soon to have the test checked to see where I am.