THE URINE 403 



For determination of urea excretion the patient drinks 200 c.c. water and one- 

 half hour later empties his bladder. Commencing at this we wait seventy-two 

 minutes (one-twentieth of twenty-four hours) and then collect the urine for urea 

 determination. 



The blood for urea determination should be taken midway in the period of col- 

 lection of the urine thirty-six minutes after the bladder is voided. 



Salt Retention. As a test for salt retention Schlayer advises giving 

 10 grams of NaCl to a patient having a salt equilibrium as the result 

 of a known diet continued over several days. This added salt should 

 be eliminated in the urine within twenty-four hours or certainly by 

 forty-eight hours. Monakow in a similar way gives 20 grams of urea 

 at one dose and this added urea should be eliminated in twenty-four 

 to forty-eight hours to show normal nitrogenous output. 



A case of nephritis may show a good urea elimination but salt retention. 



Diminished capacity to eliminate salt is a rather constant finding in all types of 

 chronic nephritis. 



Frothingham considers elimination of 8.5 grams of the 10 grams administered as 

 normal, above 4.5 grams as slight retention and below 4.5 grams as marked retention. 



Lactose Excretion. Intravenous injection of 20 grams lactose in 20 

 c.c. distilled water. The solution should be pasteurized at 8oC. for 

 three hours on three successive days. The urine is collected at one- 

 to two-hour intervals and tested with Nylander's test for sugar until 

 you get negative reaction. Normally all lactose is excreted in four 

 or five hours. 



