it depends on many factors. try Iodine first then if that doesnt work add the porcine thyroid. this can be done yourself by getting dessicated porcine thyroid from that wonderful company nutrimeds. this also takes some adjusting. after a while then decrease the glandular and see if the thyroid has kicked in. if you need it, fine. if you dont, even better.
iodine is for life - an essential nutrient with a trapper minimum daily requirement of 100mg or more.