Thyroid radionuclide uptake measurements

Tests of thyroid function based on measurements of the uptake of radio-iodine by the gland (thyroid uptake tests) constituted one of the first diagnostic applications of radioactive tracers and have been widely used in the diagnosis and investigation of thyroid diseases. In 1960 the International Atomic Energy Agency (IAEA) invited a group of consultants to draw up a standardized procedure for such uptake measurements. The recommendations of this group, herein referred to as "the 1960 recommendations", related primarily to measurements of the uptake of 131I 24 hours after its oral administration—the basis of the thyroid uptake test most commonly performed in 1960—and were published in a number of scientific journals (IAEA, 1961; 1962). During the ensuing decade, thyroid uptake tests underwent considerable development. New radionuclides were utilized, new instruments and techniques for the measurement of uptake were devised, and an increasing emphasis was placed on tests based on uptake measurements made relatively soon after administration of the radioactive tracer. Parallel development took place in tests involving the use of radionuclides but based on measurements of parameters other than uptake. In view of these advances, IAEA decided, in 1970, to convene a second panel of experts to review the status of thyroid uptake tests and to up-date, and where necessary amend, the 1960 recommendations. The Panel, whose report follows, met at IAEA Headquarters, Vienna from May 17 to 21, 1971.