140 THE DISEASES OF THE THYROID GLAND 



the vessels remained patulous, the glands however became absorbed. Ex- 

 periments on cretins likewise led to negative results. The thyroid artery 

 and vein from the upper pole of the thyroids obtained from struma operations 

 on man were united to the axillary vessels of the cretins; but here also there 

 came about a gradual absorption of the glands. Enderlen and Borst con- 

 cluded that already the slight biochemical differences that exist between 

 the tissues of different individuals of the same species are sufficient to prevent 

 a permanent functionating of the engrafted organ. 



Therefore the sovereign method of treatment to-day is still the administration 

 of thyroid-gland substance. 



Murray first proposed the treatment of myxedema with carbolated glyc- 

 erin extracts from the thyroids of animals and practised this with good 

 results. Also Kocher, Leichtenstern, Ewald, and others saw good results. 

 Since that time, however, Fox, Mackenzie, and others found that they could 

 succeed in inducing the action of the active principle also by administering it 

 by mouth; this method superseded all others and to-day is alone practised. 

 At the beginning one saw individual cases of severe acute intoxication. In 

 many of these death occurred with profuse diarrhea after the ingestion of a 

 very slight amount of thyroid-gland substance. Here the effect must have 

 been due to putrefied preparations, as the symptoms deviated from those of 

 thyroidin, and the latter appeared only after the ingestion of much larger 

 doses. 



Of the numerous thyroid-gland preparations that are found on the market 

 to-day the tablets of Burroughs, Wellcome & Co. [England] and those of 

 Parke, Davis & Co. [America] are characterized by the intensity and uni- 

 formity of their action. They consist of dried sheep thyroid and come 

 on the market in doses of 0.1-0.3 gm. 



Of other preparations I mention the thyreoidinum siccatum (Merck}, 

 thyraden (Kocher), in pills or tablets representing 0.0007 g m - iodine, and iodo- 

 thyrin or thyroiodin (Bayer), i gm. contains 3 mg. active substance or 0.3 

 mg. iodine, representing the iodine content of i gm. fresh lamb's thyroid. 



According to the investigations of Fonio, the action of thyroid prepara- 

 tions on the metabolic processes (protein decomposition, diuresis, body 

 weight, etc.) parallels their iodine content. This does not hold good for all 

 actions of the thyroid-gland substance. For instance there occurred in my 

 own experiments with iodothyrin in every dose (to 7 gm. daily) action on the 

 metabolism much greater than that on the cardiovascular apparatus. Then, 

 too, much larger doses of iodothyrin than of tabloids are needed to induce 

 symptoms of hyper thyroidism. In his substitution experiments Magnus- 

 Levy ascribes to iodothyrin the same activity as that of thyroidin. It is quite 

 undoubted that iodothyrin exerted a powerful influence on the fundamental 

 exchange of Magnus-Levy's patients yet we cannot make out from Magnus- 

 Levy's protocols whether on long-continued administration also the influence 



