METABOLISM IN NEPHRITIS 377 



night urine occurred only in the specimen corresponding to the high diet 

 and only two in whom the opposite held true. However, the amount, of 

 salt and nitrogen eliminated was greater with the large quantity of night 

 urine, indicating that the necessity of the excretion of a large amount of 

 solids by a dilute urine was the controlling factor in every instance. It 

 is thus seen that in many instances a suitable diet may do away with 

 a nocturnal polyuria and relieve the kidney from some of the strain which 

 it would otherwise be subjected to. 



Nycturia as well as a polyuria during the whole twenty-four hour 

 period has been correctly regarded as a phenomenon which compensates 

 to a certain degree for the inability of the kidney to eliminate solids by 

 concentration in the urine. Foster(a) (1916) has demonstrated how an 

 increased output of water in the nephritic patient serves to carry an 

 increased amount of nitrogenous material with it. In Bright's disease, 

 however, there is another factor to consider and this is that a polyuria, 

 implying as it does an abnormal effort on the kidney, may finally result 

 in renal fatigue and a diminished urinary output. Schlayer originally 

 substantiated this fact. The author has seen an oliguria occur after 

 glucose infusions and the ingestion of inordinately large amounts of 

 water, both of which procedures were supposed to result in exactly the 

 opposite effect. 



In the management of these problems it must be remembered that a 

 minimal level of protein metabolism is achieved by a diet high in starches 

 and low in protein, and not by starvation. When no food whatsoever is 

 taken the kidneys must eliminate about eight grams of nitrogen a day, while 

 if the starches- are forced, the amount excreted may be diminished by 

 half, thus sparing the kidney a great deal. 



The elimination of salt and nitrogen furnish some, though a limited 

 amount of information, as to renal function. If the concentration of salt 

 or nitrogen is one per cent or higher and that of urea twice as great, in 

 any specimen obtained, the power to concentrate these substances may be 

 considered to be normal, the total output then depends upon the ability of 

 the kidney to excrete water. The elimination of any solid material in 

 the urine is controlled by these two factors, degree of concentration and 

 volume of fluid elimination, and must be judged accordingly. 



The fact that the sodium chlorid concentration may be much diminished 

 while that of the nitrogen or urea remains high has already been alluded 

 to. (Table 30.) This relation is especially characteristic of myocardial 

 insufficiency and acute or chronic nephritis associated with edema. In 

 general it has been observed time and again, that the power of the kidney 

 to excrete salt is curtailed before the ability to eliminate nitrogenous sub- 

 stances is involved to the same extent. 



The total quantities of salt, urea or nitrogen put out in 24 hours and 



