THE PHYSIOLOGIC ACTIVITY OF TETRABROM-THYRONINE AND TETRACHLORTHYRONINE*

Abstract

In a search for compounds which might depress the pituitary without at the same time increasing the tissue metabolism excessively, the Br and Cl analogues of thyroxin (tetrabromthyronine and tetrachlorthyronine) were analyzed for their physiol. activity in patients with myxedema. The Br compound was assayed in 2 cases and the Cl compound in 3 cases. Material was admd. intraven. The results of assay indicate that thyroxin is about 17 times as strong as tetrabromthyronine and about 250 times as strong as tetrachlorthyronine. The Br compound was given orally to a Graves'' disease patient in 5- to 20-mg. dosage for 29 days. Metabolism dropped slightly and serum protein-bound I dropped sharply.