METABOLISM IN NEPHRITIS 



325 



The disproportionately rapid accumulation of urea in the blood is a 

 phenomenon characteristic not only of nephritis but of any condition in 

 which renal insufficiency exists. Thus in a case of polycystic kidneys 

 (Table 9) and in a dog upon whom double nephrectomy had been per- 

 formed (Table 10) the same rise in the percentage of urea nitrogen may 



be noted. 



TABLE 9 



DATA FROM A CASE OF CONGENITAL POLYCYSTIC KIDNEYS. THERE is A HIGH PERCEN- 

 TAGE OF UREA N IN THIS PATIENT WHO MAY BE CONSIDERED TO EXHIBIT A TYPE 

 OF RENAL INSUFFICIENCY Nor COMPLICATED BY ABNORMAL METABOLIC CONDITIONS 

 IN ANY OTHER TISSUES. (Mosenthal and Hiller. ) 



TABLE 10 



DATA FROM A NEPHRECTOMIZED DOG. THE PERCENTAGE OF THE UREA N RAPIDLY RISES. 



(Mosenthal and Hiller.) 



It may be concluded that under normal conditions the urea nitrogen 

 composes about 80 per cent of the non-protein nitrogen in the urine and 

 about 50 per cent of that in the blood. The selective excretory action of 

 the kidney maintains these relations; when renal function becomes im- 

 paired, from any cause whatsoever, the percentage of urea nitrogen in 

 the blood, approximating that present in the urine, rises, and is maintained 

 at the higher level whether the total non-protein nitrogen of the blood is 

 high or low; if normal renal function is again attained, as occurs in many 

 cases of acute nephritis, the blood urea drops to its usual level. This per- 

 centage relation of the urea nitrogen to the total non-protein nitrogen may 

 be advantageously utilized as a measure of renal function. The rela- 

 tion of the urea to the other non-protein nitrogenous constituents of the 

 blood will be taken up in the succeeding chapters. 



