THE TRAPPING OF IODINE AND PERTECHNETATE BY NORMAL, MULTINODULAR AND DYSHORMONOGENIC THYROID GLANDS

Iodine uptake tests have played an important part in the early development of Nuclear Medicine as the specificity of the radionuclide super(131)I enabled useful results to be obtained, even using the relatively crude equipment then available. In those days uptake measurements were made at 24 and 48 hours which had the twin advantages of minimizing background activity and allowing the long counting times which were necessary because of the small amounts of tracer used. Over the past ten years, iodine uptake tests have been largely replaced by radio-immunoassay techniques, and so iodine uptake studies are now largely restricted to T3 suppression tests and perchlorate discharge tests (PDT), both of which are unpopular because of the considerable time they take.