534 ABNORMALITIES IN METABOLISM 



obstruction, the symptoms are quite different from those observed 

 in the uremia following a chronic nephritis; drowsiness, weakness of 

 heart action, and syncope being the chief manifestations of obstructive 

 uremia, the convulsions and other manifestations of nervous irritation 

 characteristic of uremia in chronic nephritis being absent.^'' 



Chemical Changes in Uremia.— The attempts to isolate from the 

 blood and organs of uremic patients or animals toxic substances that 

 explain the manifestations of uremia have thus far failed. That 

 there is an actual retention of organic substances in the blood in 

 uremia is shown conclusively, however, by the studies of the phj^sico- 

 chemical properties of the blood. It has been repeatedly found that 

 in uremia the freezing-point of the blood is reduced markedly below 

 the normal ;^^ instead of the normal depression of 0.55°-0.57° the 

 freezing-point is usually reduced more than -0.60°, and sometimes as 

 much as -0.75°, which shows that the number of molecules in the blood 

 is increased. ^^ At the same time, the electrical conductivity may not 

 be at all increased (Bickel),^^ but may even be reduced; and as the 

 electrical conductivity of the blood depends upon the number of 

 dissociable molecules, chiefly inorganic salts, these are evidently not 

 increased.^'* Therefore, the increased number of molecules must 

 represent an excess of organic molecules that dissociate but little if 

 at all, and hence are not conductors of electricity. Some authors, 

 indeed, have ascribed uremia to the increased osmotic pressure of 

 the blood from the retained molecules, but tliis is improbable, accord- 

 ing to Strauss,'^ who found that a marked increase in molecular con- 

 centration may occur without uremia, and that we may have a severe 

 uremia without increased osmotic pressure. 



Careful metabolic studies have shown that nephritics (chronic inter- 

 stitial) are not able to convert proteins into urea as rapidly or as com- 

 pletely as normal persons. ^^ Erben'^ has studied the variations in 

 the normal components of the blood during nephritis, and found 

 the albumin generally decreased in proportion to the globulin, espe- 

 cially in cases of parenchymatous nephritis; lecitliin and calcium are 

 also decreased. Rowe^^ found the serum proteins greatly lowered in 

 chronic nephritis with uremia, an increased proportion of globulin 

 being present; with uremia the total protein content is normal or 

 slightly higher, with usually increased globulin, while nephritis wilh- 



1" Chiari, however, observed true uremia, both clinical and anatomical, in a 

 man with ureteral obstruction (Verh. Deut. Path. Gesell., 1012 (15), 207). 



11 See Tieken, Amer. Med., 1905 (10). pp. 393, 567, and 822; ButtorfioUl et al . 

 Amer. Jour. Med Sci.. 1916 (151). 63. 



*" See table of freezing points of blood and elTusioiis on paj^c 355. 



" Deut. med. Woch., 1902 (28), 501. 



"See Bienenstock and Csaki, Biocheni. Zeit., 1917 (84), 210. 



" Die chronischen Nieronent/iindungen, etc., Berlin, 1902. 



loLevene el al., Jour. Expcr. Med., 1909 (11). 825. 



"Zeit. klin. Med., 1903 (50), 441; 1905 (57), 39. 



18 Arch. Int. Med., 1917 (19), 354. 



