METABOLISM IN NEPHRITIS 355 



dominated entirely by the kidney, but that they are the expression of the 

 body's power to eliminate urinary excretory products at the urethra; 

 diseases of the hypophysis, pneumonia, excessive vomiting or diarrhea, 

 fever, diabetes mellitus, renal calculus, urethral stricture, hypertrophied 

 prostate, pyelitis, cystitis, myocardial insufficiency, paralysis of the blad- 

 der, polycystic kidney, etc., may all profoundly influence renal activity 

 and mold the results of functional tests. It is obvious that in their 

 interpretation clinical judgment and knowledge will always play a larger 

 part than a set of rules which defines the limitadons of tubular or glo- 

 merular activity or even of "renal function as a "whole." 



There has been only one thorough attempt made to associate the 

 impaired function of anatomical structures (glomeruli and tubules) with 

 the pathological physiology of the kidney in nephritis. This is that of 

 Schlayer and his associates. Some of the extensive conclusions of these 

 authors are of the greatest importance, while others have not proved to be 

 of practical value ; however, they are all of considerable interest and it is 

 well worth while to take them up briefly, at least. 



Schlayer 's Theories of Renal Function in Nephritis 



The living kidney was studied by various means and the results were 

 given clinical application. The kidney was found to have two functional 

 units, the blood vessels (glomeruli) and the tubules. The excretory sub- 

 stances resorted to as criteria for the efficiency of these structures were 

 water, which is controlled by the glomerular activity, and salt, which is 

 eliminated by the tubules. Inasmuch as these materials form part of the 

 body's tissues, it is evident that extrarenal factors may influence the 

 amounts present in the urine. Therefore, in addition, test materials were 

 chosen which should not be affected by extrarenal influences. These 

 were lactose which was found to represent the activity of the blood vessels, 

 while potassium iodid was regarded as an excretory product of the tubules. 

 The only extrarenal factor affecting the excretion of these substances 

 is passive congestion which delays the elimination of lactose. 



Various degrees of damage to the blood vessels result in the excretion 

 of very changing quantities of urine. A slight impairment produces an 

 irritability or hypersensitiveness of the blood vessels and brings about a 

 polyuria ; a further weakening of the vascular function causes the urine 

 volume to diminish and resemble the normal quantity, the stage of "nor- 

 maluria" ; finally, marked impairment results in oliguria. Table 24 on 

 page 356 illustrates this conception. 



The underlying principle that a slight lesion may result in super- 

 function and only a severe impairment produces hypofunction, as meas- 

 ured by any of the conventional tests, holds true for the kidney and 

 probably for the activities of many other organs. This phenomenon is al- 



