371 



The criteria for judging of the efficiency of the kidney by means of 

 this test are : 



1. The variation of the specific gravity in the different specimens of 

 urine collected. 



2. The'maximal specific gravity attained by any specimen. 



3. The quantity of night urine. 



4. The concentration of sodium chlorid, urea, or total nitrogen in any 

 of the specimens. 



5. The total quantity of sodium chlorid, urea Or total nitrogen elimi- 

 nated. 



The degrees of variation of the specific gravity from the highest to the 

 lowest value obtained in the normal individual is 9 or more. An example of 

 this is given in Table 27. 



TABLE 27 



EXAMPLE OF NORMAL RESULT WITH TEST DAY FOB RENAL FUNCTION. NOTE THE VARIA- 

 TIONS IN THE SPECIFIC GRAVITY, Low AMOUNT OF NIGHT URINE, THE VARIATIONS 

 IN THE CONCENTRATION OF SALT AND NITROGEN, AND THE RISE OF THE CONCENTRA- 

 TION OF SALT AND NITROGEN TO MORE THAN ONE PER CENT IN CERTAIN SPECIMENS. 

 (!N THE ROUTINE PERFORMANCE OF THE TEST THE SALT AND NITROGEN, OR UREA 

 NEED NOT BE DETERMINED IN EVERY SPECIMEN AND MAY BE OMITTED ENTIRELY IF 

 THEY YIELD No DESIRED INFORMATION.) (Mosenthal, 1915.) 



Under certain circumstances, if too little water is taken, or in very 

 hot weather when the fluid excretion of the urine is diminished because 

 of loss of water in other directions, the variations in the specific gravity 

 may be lower than normal and it may be fixed at a somewhat higher level. 

 This has been stressed by Lyle and Sharlit. An example of this sort is 

 given in Table 28. 



