I recently provided a review of Iodine-131 use in Hyperthyroidism. Subsequently a comment was made about using Technetium 99m as an alternative, and my book quoted. Technetium 99M can only be used to VISUALIZE a thyroid during radiography, not actually destroy it. Only the radioactive iodides I-131, I-125 actually destroy the thyroid tissue. I wanted to clarify this. *********************************** T.W. Hale, Ph.D. Associate Professor of Pediatrics Texas Tech University School of Medicine ***********************************