I have to take Synthroid for the rest of my life. My thyroid was under producing and that will cause a goiter too. Salt with iodine included is one way to prevent a lot of thyroid under producing. The hospital 'killed' my thyroid with radiation. My Dr. told me many women will take the Synthroid for years then decide they don't need it. They very slowly descend into lethargy and death. The metabolism will slow down to being in a coma. That scared me so bad I'll never stop taking it.