UREMIA 433 



first in order of importance stand uremia and cholemia (the 

 latter has already been considered in connection with the discus- 

 sion of Icterus, Chap. xvi). Of apparently less significance are 

 autointoxications due to failure of elimination of gaseous meta- 

 bolic products by the lungs, and failure of the excretory func- 

 tions of the skin. 



UREMIA 1 



The cause or causes of the severe, often fatal, intoxication 

 that may occur when the outflow of urine is completely checked, 

 or when it is qualitatively and quantitatively altered for long 

 periods of time, have not yet been definitely determined. As 

 the kidney seems to be the chief organ for the removal of the 

 products of nitrogenous metabolism, it is naturally assumed 

 that uremia is the result of a retention of these products, but as 

 yet it has not been ascertained which of the many products is 

 responsible, and, indeed, there are very good reasons for question- 

 ing if the substances present in normal urine do or can cause 

 uremia when their elimination by the kidney is defective. There 

 is no question but that the urine contains toxic substances. 

 Among them are the salts of potassium, which, however, can- 

 not alone explain all the urinary toxicity, for the symptoms 

 produced by the injection of urine are different from those pro- 

 duced by potassium salts, and it has been found that the inor- 

 ganic constituents (ash) of urine are less poisonous than the 

 entire urine. Furthermore, toxic mixtures of organic, ash-free 

 substances have been obtained from normal urine. 2 Of the 

 known normal constituents of the urine there are few, however, 

 that are toxic to any considerable degree, and these occur in but 

 very small quantities. Urea is generally considered as almost 

 absolutely non-toxic, 3 the animal body withstanding injection 

 of large quantities without appreciable injury. Uric acid, the 

 purin bases, hippuric acid, creatinin, and the urinary pigments 

 are all possessed of very slight toxicity, and their effects do not 

 explain the manifestations of uremia. Injections of urine into 

 animals may cause more or less disturbance, but it is different, 

 on the whole, from the manifestations of uremia. (The experi- 

 ments of Bouchard and his school present such serious errors 



1 General re'sume' with literature by : Honigmann, Ergeb. der Pathol., 1894 

 (Bd. 1, Abt. 2), 639; 1902 (8), 549; Ascoli, Vorlesungen iiber Uramie, Jena, 

 1903. 



2 See Dresbach, Jour. Exp. Med., 1900 (5), 315. 



3 Herter ascribes more importance to urea in uremia than do many other 

 authors (see Johns Hopkins Hospital Keports, 1900 (9), 69). 



28 



