UREMIA 529 



shall, and \'aii Slykc, has enabled us to obtain exact knowledge of 

 many of the chemical changes of nephritis and uremia."^ It has been 

 found that the normal blood contains from 20 to 30 mg. of nitrogen 

 in noncoagulable form in each 100 c.c, there being usually about 5 

 mg. increase after meals, and ordinarily about one half, or a little 

 more, of this nitrogen is in the form of urea. In all conditions that 

 impair renal function, whether renal changes or circulatory deficiency, 

 there is a rise in this noncoagulable nitrogen, and when there is ex- 

 cessive tissue destruction there may also be a slight rise independent 

 of renal injury. As a general rule, but with some exceptions, the 

 amount increases with increased renal impairment, the highest figures 

 being seen in uremia, in which figures as high as 350 mg. have been 

 obtained. Tn 130 uremics, Foster found the average to be 84 mg. of 

 nitrogen. There is no constant relationship between the blood pres- 

 sure and the nitrogen figure, but functional tests usually show a cor- 

 respondence between the excretory power of the kidney and the re- 

 tention of metabolites in the blood. The symptoms of asthenic uremia 

 are rarely well defined when the concentration of urea in the blood is 

 less than 100 mg. per 100 c.c, and thej^ are rarely absent Avhen the 

 concentration exceeds 200 mg.-* 



Along with the other nitrogenous constituents the uric acid is in- 

 creased from a normal 2 to 3 mg. up to 7 to 10 mg., and even higher. 

 Creatinine rises from 1 or 2 mg. up to 5 to 20 mg.-'' On the other 

 hand the amino-acid nitrogen may be normal in the blood even with 

 extremely high nonprotein nitrogen figures,^" although sometimes it is 

 much increased, as high as 30 mg. amino acid N having been found by 

 Bock ^"^ in uremia (the normal figure being 7 mg.). Ammonia nitro- 

 gen may show a slight increase, rising in half of Foster's cases from the 

 normal 0.5 mg. to from 0.7 mg. to 2.2 mg. per 100 c.c. Indicanemia 

 may also be present, but it is not a toxic factor. (Dorner.)^^ The 

 blood normally contains about 0.05 mg. per 100 c.c. ; in uremia it 

 may rise to 0.2 mg., and as much as 2.2 mg. has been found in one 

 case.^- 



The Etiology of Uremia. — The fact that the highest figures for 

 non-protein nitrogen are usually found in uremia might be accepted 

 as proving that uremia is caused by poisoning with these metabolites, 

 were it not for certain contradictoiy observations. 



27 Good I'eviews and l)ihlioo;raphips are given hv Tileston and Comfort, Arch. 

 Int. Med., 1914 (14), 620; Schwartz and :\rcGill', ibid., 1910 (17). 42: Woods, 

 ibid., 1915 (16), .577; Karsner, Jour. Lab. Clin. :Med., 1916 (1), 910. 



28 Hewlett, Cxilbert and Wickett. Arcli. Int. Med., 191G (18). 6.36. 



29 See :Mvers and Fine, Arch. Int. :Med , 1915 (16), 536; 1916 (17), 570. 



30 Foster, Arch. Int. INled., 1915 (15). 356. 

 •"■oa .Tour. Biol. Chem., 1917 (29), 191. 



31 Deut. Arch. klin. :Med., 1914 (113), 342: Rosenberg Arch. exp. Path.. 1916 

 (79), 260: TscherkotT, Deut. nied. Woch., 1914 (40), 1713. 



32Hass, Deut. Arch. klin. Med., 1916 (119), 177. 

 34 



