RADIOTHYROXINE TURNOVER STUDIES IN MYXEDEMA, THYROTOXICOSIS, AND HYPERMETABOLISM WITHOUT ENDOCRINE DISEASE

Abstract

In a previous report (1) the disappearance curves of 181-11Abeled L-thyroxine and L-triiodothy- ronine were described in euthyroid subjects. The radioactive compounds were injected intrave- nously, and the radioactivity of the plasma or se- rumnwas determined at intervals for approximately two weeks. Estimations were made of the rate of degradation of organic (thyroxine) iodine. In the present woxk, this approach has been extended to myxedernatous and thyrotoxic patients with findings agreeing in general with Ingbar and Freinkel (2) whose methods were similar, as well as Berson and Yalow (3) who employed entirely different methods. In the effort to elucidate the role of peripieral tissue metabolism in hormone degradation rate, studies were carried out during treatment of myxedema, and in subjects exhibiting hypermetabolism without evidence of endocrine disease.