THE MEASUREMENT OF THYROIDAL IODINE UPTAKE SOON AFTER THERAPY WITH RADIOIODINE*

Abstract
Serial observations of residual radioactivity in the region of the thyroid gland and of urinary excretion of radioiodine were made during the early period after giving a therapeutic dose of I131. Blocking the thyroid with potassium perchlorate increased the urinary excretion of I131 and increased the rate at which thyroidal radioactivity diminished. Assuming dynamic equilibrium between the several iodide compartments of the body, the thyroidal iodine uptake rate may be derived from such observations.