STUDIES of synthetic sodium /-thyroxine demonstrate that as an oral medication in dosage of 0.5 mg. or less daily it is calorigenic and clinically active.1 In similar dosage it has been shown to reduce the uptake of radioactive iodine.2 Triiodothyronine, recently identified, synthesized, and demonstrated in human serum,3 also has been shown to be clinically effective4 and to be several times as potent as thyroxine.5
Curiosity as to the possible effect of sodium d-thyroxine led us to carry out tests with this substance. It was difficult to obtain. Dr. Leonard Ginger, of the Baxter Laboratories, Inc., Morton Grove, Ill., the source of the levo form used in our clinical studies, produced it for us. It has already been demonstrated by Greer6 that inorganic iodine in amounts equal to that in these medications has no effect upon uptake of radioactive iodine. We have, however, carried out a few tests at four-dose
STARR P, LIEBHOLD-SCHUECK R. THEORY OF THYROID HORMONE ACTION: Conclusions Derived from Differences in Effect of Sodium /-Thyroxine, Sodium d-Thyroxine, Triiodothyronine, and Potassium Iodide on Uptake of Radioactive Iodine by Thyroid Gland of Normal Human Subjects. AMA Arch Intern Med. 1953;92(6):880–888. doi:10.1001/archinte.1953.00240240116008
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