Whole-Body Counting of131I-Labeled Thyroxine

Abstract
A technique is described for measuring the absorption and degradation rate of I131 "labeled thyroxine in human subjects; the amount of tracer material remaining in the extrathyroidal pool is deduced from external in vivo thyroidal and whole-body counting. Allowance is made for fecal excretion and fecal retention of labeled material. Results obtained in 24 euthyroid subjects are reported.