A toxic nodular goiter (TNG) is a thyroid gland that contains autonomously functioning thyroid nodules, with resulting hyperthyroidism. There are distinct considerations if the patient has a single solitary toxic nodule (see Solitary Thyroid Nodule). TNG, or Plummer’s disease, was first described by Henry Plummer in 1913. TNG is the second most common cause of hyperthyroidism in the Western world, after Graves disease. In elderly individuals and in areas of endemic iodine deficiency, TNG is the most common cause of hyperthyroidism.