Evidence for a Non-Calorigenic Effect of Thyroxin on Erythropoiesis as Judged by Radioiron Utilization.

Abstract

Summary Thyroxin has been shown to have an effect on erythropoiesis, as judged by Fe59 uptake, which is greater than would be expected from its influence upon oxygen consumption. This non-calorigenic effect on erythropoiesis has been shown in 4 ways—1) by observing a greater percentage increase in Fe59 incorporation than in oxygen consumption in hypophysectomized thyroxin treated rats; 2) by observing an increase in Fe59 uptake in thyroxin treated polycythemic hypophysectomized rats where the increased number of erythrocytes should take care of any erythropoietic response to oxygen need; 3) by finding that thyroxin induced a greater erythropoietic response in thyroidectomized rats than did dinitrophenol even when the latter drug induced a higher oxygen consumption, and 4) by noting that thyroxin treated thyroidectomized polycythemic rats responded by an elevation in Fe59 uptake while dinitrophenol in similar rats had no effect.