Because the thyroid needs iodine to produce hormones, it takes up the radioiodine, which destroys the overactive thyroid cells over time.

CNN: Graves' disease

Manhattan psychiatrist Drew Ramsey recalled that early in his career, he examined a patient with daily panic attacks and noticed a swelling on her shins, a classic sign of Graves' disease, a form of overactive thyroid that can cause severe anxiety.

WSJ: Confusing Medical Ailments With Mental Illness