("HAPTi:il XXII 



CHEMICAL PATHOLOGY OF THE DUCTLESS GLANDS' 



DISEASES OF THE THYROID- 



As we have much evidence that the thyroid has a marked infhieiice 

 upon metabohsm, and also that it may be of imp^ortance in preventing 

 and in producing autointoxication, the chemistry of diseases of the 

 thyroid may be appropriately considered in connection with the auto- 

 intoxications. 



The Functions of the Thyroid 



Metabolic Function. — That the thyroid has an impoitant rela- 

 tion to metabolism, especially of proteins, is shown by the following 

 facts: 



(1) Administration of the gland substance, or active preparations made from 

 it, to_ healthy men or animals, causes a greatly increased elimination of nitrogen in 

 the form of area." This nitrogen comes not only from the food, but also from in- 

 creased tissue-destruction, as is shown by the loss of weight and strengtli, and by 

 the increased excretion of sulphur and phosphorus. An increased destruction of 

 the body fat also occurs, so that thyroid therapy has been found efficient in the 

 treatment of obesity, but often dangerous because of the relatively great amount 

 of tissue-destruction. Basal metabolism is most markedly raised in hyperthyroi- 

 dism, and is lower in cretinism and myxedema than in any other disease* 



(2) Loss of thyroid tissue, either through operation or disease, greatly reduces 

 both nitrogenous metabolism and oxidative processes. Administration of thyroid 

 preparations under these conditions will bring the nitrogen elimination and the 

 gas exchange back to normal. 



(3) Dehcient thj-roid secretion in 3'oung animals prevents their developing nor- 

 mally, the amount of deficiency varying from nearly total lack of development in 

 extreme cretinism to slight grades of defective development (infantilism) or de- 

 layed maturity. In adult animals, besides decreased metabolism there occur also 

 various trophic changes in the skin and its appendages, an increased amount of 

 mucin-Iike material in the tissues, and greatly decreased nerv^ous and mental ac- 

 tivity. All these conditions are relieved to greater or less degree by administration 

 of thyroid tissue or its preparations.^ Evidently, therefore, the thyroid exerts an 

 influence upon growth and tissue changes; whether this depends upon its influence 

 upon metabolism, or is an independent and specific function, cannot be deter- 

 mined.^ 



^ Thorough reviews of the entire subject of the ductless glands are given by 

 Biedl, "Innere Sekretion," Urban and Schwarzenberg, Berlin, 11)13; and Vincent, 

 Ergebnisse Physiol., 1910 (9), 451; 1911 (10), 218. 



- Concerning the thyroid see besides Beidl and Vincent, the review bv Bircher, 

 Ergebnisse Pathol., 1911, XV d), 82; Crotti, "'Thyroid and Thymus," Phila., 1918. 



* See Rohde and Stockholm, Jour. Biol. Chem., 1919 (37), 305. 



* Du Bois, Arch. Int. Med., 1916 (17), 915. 



* Concerning the influence of thyroid on skeletal growth see Holmgren, X'ordiskt 

 Med. Arkiv, 1910 (43), No. 2. Literature given by Basinger, Arch. Int. Med., 

 1916 (17), 260. 



^ See the interesting experiments of Gudernatsch (Arch. Entwickl., 1912 (35), 

 457; Amer. Jour. Anat., 1914 (15), 431; Anat. Record, 1917 (11), 357), who found 

 that feeding thyroid to tadpoles hastens their differentiation but checks growth; 

 also removal of the thyroid from tadpoles increases growth but delays or entirely 

 prevents metamorphosis (Hoskins, Jour. Exp. Zool., 1919 (29), 1). 



597 



