ABSTRACT
The use of radionuclides in clinical laboratory methodology is fairly recent, and there has been an explosion of procedures related to this sensitive measurement parameter. One of the first radioisotope tests used to diagnose thyroid disease was the 24- or 48-hr excretion of radioiodine in the urine. One of the limitations to radionuclide methodology is that a special license is required. In general, the license is not difficult to obtain. Perhaps the most important advantage in the use of radioisotope methods is their exquisite sensitivity. These methods determine much smaller quantities of materials in urine than existing chemical or physical measurements. It is important to use precise technique with radioactivity and to follow directions explicitly. In addition, the counting instrumentation must be checked daily to make sure the wells have not been contaminated. Quality control materials should be used each day.
