CHAPTER LXXIII 

 URIC ACID AND THE PURINE BODIES (Cont'd) 



SOURCE OF ENDOGENOUS PURINES 



Even after the entire elimination of all purine substances from the 

 food in the case of man, purine continues to be excreted in the urine 

 as uric acid. This, as above remarked, is called endogenous excretion. 

 At first it was thought by Burian and Schur that the total nitrogen of 

 the purine-free diet could be considerably varied without causing any 

 alteration in the amount of the endogenous purine excretion, but a rep- 

 etition of the work has shown that, when these* changes are of consider- 

 able magnitude, the endogenous moiety does not remain constant. This 

 has already been demonstrated in the table on Folin's results (see page 

 614), and is still better illustrated in the accompanying table, which 

 shows the excretion of uric acid and coincidently of urea from hour to 

 hour in the urine after taking food which is free from nuclein or purine 

 substances. After a fast of six hours, a diet consisting of bread and 

 potatoes was taken at 1:30, and the urea and uric acid measured in the 

 urine each hour thereafter.* 



(Hopkins and Hope.) 46 



A postprandial increase of endogenous purine excretion is very dis- 

 tinct, and it indicates that during the process of assimilation something 

 must be occurring in the organism which entails the production of purine 



*These investigations should be repeated, since there is some question as to whether the method 

 of analysis employed (Folin-Shaffer) is suitable for determining hourly uric-acid excretion. 



643 



