CHAPTER XX 



CHEMICAL PATHOLOGY OF THE DUCTLESS 



GLANDS 1 



DISEASES OF THE THYROID - 



As we liave miieh evidence that the thyroid has a marked influence 

 upon metabolism, and also that it may be of importance in preventing 

 autointoxication, the chemistry of diseases of the thyroid may be ap- 

 propriately considered in connection with the autointoxications. 



THE FUNCTIONS OF THE THYROID 



Metabolic Function. — That the thyroid has an important relation 

 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 urea. This nitrogen comes not 

 only from the food, but also from increased tissue-destruction, as is 

 shown by the loss of weight and strength, and by the increased ex- 

 cretion 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 rela- 

 tively great amount of tissue-destruction. Basal metabolism is most 

 markedly raised in hyperthyroidism, 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) Deficient thyroid secretion in young animals prevents their de- 

 veloping normally, the amount of deficiency varying from nearly total 

 lack of development in extreme cretinism to slight grades of defective 

 development (infantilism) or delayed maturity. In adult animals, 

 besides decreased metabolism there occur also various trophic changes 

 in the skin and its appendages, an increased amount of mucin-like 

 material in the tissues, and greatly decreased nervous and mental ac- 



1 Thorough reviews of tin- ciitiic sulijcct (if llic diictlfss glands nro lmvcii hy 

 Biedl, "Tnnero Sekretioii,"' rrhaii and Scliwar/ciilK'rjr. r>crlin. ini;i: and Vincent, 

 Erffchnissc I'livsioi.. lltlo (!)), 451; 11)11 (10). 21S. 



- Coiicerninfr tlie thyroid see besides iiiedl and \'ineent, the review bv llirelier, 

 Ergebnisse Pathol., 1011, XV (,), 82. 



iiaDu Bois, Arch. Int. Med., 1916 (17). i)15. 



590 



