THE THYROID GLAND AND ITS DISEASES 237 



The discovery of iodin in the thyroid gland by Baumann and the claim 

 that "thyroidin" was the "active principle" of the organ led observers 

 to test the action of this last upon metabolism, and to compare its activity 

 with that of the crude gland. Treupel, Grawitz and others, experi- 

 menting on the human subject, and Roos (a), who used a small dog, came 

 to the conclusion that Baumann's "thyroiodin" influences metabolism in 

 the same way as the thyroid gland substance itself, that is to say, the body 

 weight diminishes and the nitrogen excretion increases. 



Magnus-Levy (a) devoted special attention to the respiratory gas ex- 

 changes during thyroid administration. In normal individuals there was 

 no very constant increase of the oxygen intake and the carbonic acid out- 

 put. The effects were more marked in myxedematous patients. Thyro- 

 iodin showed qualitatively the same effects as thyroid gland substance. 

 Potassium iodid did not produce the same effects. 



Similar results have been obtained by other observers. 



In all these experiments (which were of short duration) the increase 

 of oxidation processes proves that the greater part of the loss of weight 

 under thyroid feeding is caused by destruction of fat. The careful experi- 

 ments of Schondorff showed that after a certain period the protein is also 

 attacked. 



Considerable evidence has been accumulated that the metabolic activity 

 of thyroid preparations depends on the amount of iodin present. Oswald 

 (e), who worked with his a thyreoglobulin," found that a preparation poor 

 in iodin produced little or no effect upon metabolism, while one rich in 

 iodin produced a marked increase in the nitrogen excretion. Marine and 

 Williams reached similar conclusions in regard to the efficacy of thyroids 

 containing varying proportions of iodin. 



According to Cramer, who gives full references, the administration 

 of thyroid reduces the liver glycogen to a. trace. He considers that the 

 increased protein and fat katabolism is a secondary effect due to increased 

 mobilization of the liver glycogen. 



Frontali and Hunter (&) report the elimination of very large quan- 

 tities of creatin in sheep and dogs after thyro-parathyroidectomy. 



Brief reference has been made above to the effect of Kendall's thyroxin 

 upon metabolism. Plummer (quoted by Kendall) has shown that 1 mg. 

 of thyroxin in an adult weighing approximately 150 pounds increases 

 the metabolic rate 2 per cent. The curve of this response has been 

 shown to be approximately a straight line between metabolic rates 30 per 

 cent below normal to 15 to 20 per cent above normal. 



Quite recently Abelin has declared that certain amins derived from 

 protein have the same action on metabolism as the administration of the 

 thyroid gland itself. 





