URIC ACID. 595 



uric acid after a meal is by no means marked, unless the food taken contains 

 nuclein. On a diet composed, for instance, of egg albumin, the rise was very 

 small, while during the digestion of non-nitrogenous diet the output of uric 

 acid was even diminished. Camerer holds, therefore, that digestive leuco- 

 cytosis cannot be the cause of post-prandial increase, but only the actual 

 ingestion of nucleins, and his results would suggest that we must answer the 

 question in the previous paragraph in the affirmative, and recognise that 

 the excretion of uric acid is not increased by the ingestion of ordinary 

 proteids. 



If this be confirmed, we must for the future attach no importance to the 

 urea : uric add ratio ; and when we wish to eliminate mere dietetic effects 

 from our study of other specific variations in the urinary uric acid (when, for 

 instance, we are endeavouring to ascertain if retention is occurring in disease, 

 or whether a certain drug is promoting elimination), we must do this by 

 controlling the ingestion of nucleins during the experiments. 



It should be understood, however, that in spite of much labour spent 

 upon the problem, our knowledge of the relation of urinary uric acid to 

 diet is scarcely yet upon a firm foundation, and contradictory statements 

 will be found in the literature. Future investigators may have to face 

 yet another difficulty, if it be true, as Weintraud l affirms, that a true 

 excretion of uric acid may occur through the walls of the intestine. 



One fact is abundantly certain that great individual differences 

 exist in uric acid excretion. In spite of all that has been said above, it 

 is found that, with the ordinary regularity of habits and diet customary 

 in civilised life, the uric acid output (when the whole twenty-four hours' 

 excretion is dealt with), and even its relation to urea, will remain fairly 

 constant in any given individual ; whereas, when different individuals 

 are compared, much greater differences are seen. Before we can say 

 with certainty what constitutes a pathological or exceptional condition 

 in any case, we must know the normal behaviour of the particular 

 organisation in question (Salkowski). 



The ratio borne to urea may vary in different healthy individuals 

 from 1 : 25 to 1 : 50 ; the proportion most commonly found being from 

 about 1 : 35 or 1 : 40. 



(b) Variations apart from diet. It is a well-established fact that 

 in newly -born children the uric acid excretion bears a high proportion 

 to the body weight, and also to the other nitrogenous constituents of 

 the urine. In the first few days of life 7'8 per cent, of the urinary 

 nitrogen may be in the form of uric acid. 2 



The absolute amount is increased by excessive exercise and 

 diminished by rest. With regard to drugs, the action of alkalies is 

 still disputed. It is possible that an isolated dose may temporarily 

 accelerate excretion ; but, according to Spilker and Salkowski, 3 continued 

 administration diminishes it. There is certainly no foundation for the 

 statements of Haig, that the excretion of uric acid varies inversely as 

 the acidity of the urine. 4 Salicylates undoubtedly increase the amount 

 in the urine. Pilocarpine produces an increase, possibly from the 

 leucocytosis which follows its use. Pathologically, there is increase in 



1 Ohem. Centr.-BL, Leipzig, 1895, Bd. ii. S. 310. 



2 Hofmeier, Vircliow's Archiv, 1882, Bd. Ixxxix. S. 493. 



3 Ibid., 1889, Bd. cxvii. S. 570. 



4 Of. Herringliam and Davies, also Herringh&m and Groves, Journ. PhysioL, Cambridge 

 and London, 1891, vol. xii. pp. 475 and 478. 



