CHEMISTRY OF THE PARATHYROIDS til 3 



The Parathyroids'" 



The parathyroids were originally considered as but a form of undeveloped 



accessory thyroids, but they are now generally believed to be independent organs 

 of fully as great importance as the thyroid. Tiieir independence is conclusively 

 shown by tlie cases of cretinoid ciiildren in whom the thyroid proper has fiiiled to 

 develop, while the parathyroids are found to be normal," thus proving their 

 distinct origin, the iiuibility of parath\ roid tissue to change into thyroid tissue,'* 

 and their inability to prevent the changes of cretinism.'^ Parathyroids contain 

 no appreciable amounts of iodin (Estes and Cecil),'-' although 14 per cent, of para- 

 thyroids obtained at autopsy contain a colloid material (Thompson and Ilarris)." 

 Glycogen is demonstrable in the epithelium. To their removal are ascribed by 

 many investigators the acute manifestations of athyreosis, while tlic more clironic 

 changes of my.xedema are attributed to the loss of the thyroid. MacCJallum's 

 studies support this view, for he found the results of parathyroidectomy in dogs 

 very different from the results of thyroidectomy. The most prominent symptoms 

 are muscular twitchings, gradual!}' passing into tetanic spasms, and due to nervous 

 impulse rather than to muscular changes, since they did not appear in muscles 

 from which the nerve-supply has been cut off. Trismus, protrusion of the eyes, 

 and rapid respiration without cyanosis (i. e., air hunger) were al.so observed, and 

 death usually resulted from exhaustion. Apparently these symptoms are due to 

 some toxic substance which accumulates on account of the absence of the para- 

 thjToids, for it was found that simply diluting the dog's l)lood by withdrawing 

 part of it, and injecting a corresponding amount of salt solution, caused a tempor- 

 ary cessation of the tetanic symptoms; and injections of emulsions of parathyroid 

 checked the symptoms for some time, presumably through neutralizing the hypo- 

 thetical poisons. Degenerative changes that were observed in the cerebral ganglion- 

 cells also favor the view that some unneutralized toxin is responsible for the 

 symptoms following parathyroidectomy. On the other hand, profound mental 

 symptoms and insomnia have resulted from feeding parathyroid toman.'"' Recent 

 studies make it seem probable that tetany parathyreopriva and idiopathic tetany 

 are either identical or very closely related.'^ 



The metabolism after parathyroidectomy may show the following changes:'* 

 There is a reduction in the assimilation limit for carl)ohydrates (Hirsch, Under- 

 bill'* and others). There is a disagreement concerning inorganic metabolism, for 

 while MacCallum and Voegtlin-" found an increased elimination of calcium and 

 a loss of the same element from the blood and brain (which they would make 

 responsible for the increased nervous irritaliility), Cooke found no such loss of 

 calcium,-' but she did find an increased urinary excretion of magnesium. Ac- 

 cording to most observers, nitrogenous metabolism is altered as shown by the in- 

 creased excretion of nitrogen, and especially of ammonia. Greenwalci-- found 

 increased ammonia less conspicuous than increased undetermined nitrogen and 

 sulphur, and decreased phosphorus excretion. There maj' occur an increase in 

 the bases of the blood (alkalosis, q. v.) which disappears under the acidosis that 

 results from tetany.-^ 



In view of the conflicting facts, the theory that the increased irritability and 



1° A review of this subject is given by Thompson in "The Surgery and Pathol- 

 ogy of the Thyroid and Parathyroid Glands," by A. J. Ochsnerand R. L. Thomp- 

 son, St. Louis, 1910. See also MacCallum, Krgeb. inn. Med., 1913 (11), 569. 



11 Roussv and Clunet, Compt. Rend. Soc. Biol., 1910 (68), 818. 



12 See Edmunds, Jour. Path, and Bact., 1910 (14), 288. 



13 See MacCallum, Johns Hopkins Hosp. Bull.. 1907 (18), 341. 



^* Ibid., 1907 (18), 331; also Cameron, Jour. Biol. Chem., 1914 (16), 465. 



15 Amer. Jour. Med. Sci., 1908 (19), 135. 



i« Morris, Jour. Lab. Clin. Med., 1915 (1), 26. 



'^ See Paton and Findlay, Ouart. Jour. Exp. Physiol., 1917 (10), 203. 



18 See review bv Cooke, Amer. our. Med. Sci., 1910 (140), 404. 



19 Jour. Biol. Chem., 1914 (18), 87. 



20 Jour. Exp. Med., 1909 (11). 118; 1913 (18), 618. 



21 See also Bergeim, Stewart and Hawk, J.nir. Exp. Med., 1914'(20), 225. 

 "Amer. Jour. Phvsiol. 1911 (28), 103; Jour. Biol. Chem., 1913 (14), 363. 



" Wilson, Stearns and Thurlow, Jour. Biol. Chem., 1915 (23), 89, 123. Mc- 

 Cann, ibid., 1918 (35), 553; Togawa, Jour. Lab. Clin. Med., 1920 (5), 299. 



