METABOLISM IN NEPHRITIS 



323 



blood given in the case cited under protein destruction (Table.18) repre- 

 sents approximately as high a value as is usually reached in the cases 

 with marked renal insufficiency. 



Other aspects of the subject of urea in nephritis are taken up under 

 the headings of the comparative value of uric acid, urea and creatinin in 

 the blood in nephritis, the relation of the urea to the total non-protein nitro- 

 gen of the blood in nephritis, protein destruction in nephritis, renal func- 

 tion, and uremia. 



The Relation of the Urea to the Total Non-Protein 

 Nitrogen of the Blood in Nephritis 



In nephritis, as well as in other conditions accompanied by renal 

 insufficiency, when the non-protein nitrogen of the blood rises it is accom- 

 panied by a disproportionately rapid increase of the blood urea. This 

 results in a rise of the percentage figures for the urea nitrogen of the total 

 non-protein nitrogen (Hohlweg, Obermayer and Popper, Farr and Aus- 

 tin, Tileston and Comfort (a) (&), Mosenthal and Hiller). The actual 

 percentage obtained will vary somewhat according to which method is em- 

 ploye4 to determine the non-protein nitrogen. The different coagulants 

 used to separate the protein from the non-protein part of the blood precipi- 

 tate unequal fractions. Thus, the trichloracetic method of Greenwald 

 yields considerably higher results for the non-protein nitrogen than the 

 methyl alcohol method of Folin. The following figures apply to results 

 obtained with the alcohol method of Folin. 



The normal human being usually metabolizes protein in such a man- 

 ner that approximately 80 per cent of the nitrogen set free in the blood 

 is in the form of urea. The selective action of the kidney maintains the 

 urea nitrogen at a level of 50 per cent, or less of the total non-protein nitro- 

 gen of the blood. An impairment of renal function, even of very slight 

 degree, may result in an increase in the percentage of urea nitrogen. The 

 following table gives an approximation of what is to be expected in this 

 regard. 



TABLE 6 



APPROXIMATE PERCENTAGES OF UREA N AS TOTAL NON-PROTEIN NITROGEN INCREASES IN 

 THE BLOOD. (Mosenthal and Hiller.) 



In patients whose clinical condition does not vary very appreciably, 

 the percentage of urea nitrogen remains constant whether the total non- 



