THE METABOLISM IN GOUT 423 



there is always a corresponding change in the uric acid excretion (Host). 

 Lichtwitz(Z) found this to be true, but his subject had difficulty in taking 

 the large amount of protein given and this produced only a slight increase 

 in the uric acid output. Individuals on a purin free diet usually excrete 

 between 0.3 gram and 0.6 gram daily. In the fasting state, 12 to 15 

 hours after the last meal the excretion of uric aeid sinks to a lower level 

 than it does when the patient is taking a purin free diet. This is the 

 "Nuchterwert" of Mares(a), the "Hungerstand" of Burian. Mares be- 

 lieves the uric acid output is constant for each individual, but only in the 

 fasting state. Faustka in 1914 brought support for this view by re-exam- 

 ining the subject Mares had studied in 1886 and finding the uric acid fast- 

 ing value was unchanged. 



The excretion of uric acid is less during the night than during the 

 day (Rockwood, Hirschstein(&), Leathes(a)), and the hourly variations in 

 the output are often considerable. The curve of elimination is characteris- 

 tic and Pfeil found it alike in different healthy individuals. I have noted 

 considerable variation in different subjects I have studied and also in 

 the observations published by different writers. The output is greatest 

 in the early hours of the day, that is before noon. Leathes found the maxi- 

 mum excretion between 10 A. M. and 1 P. M. Host (a) in the first half of 

 the forenoon. In a fasting subject under my observation the greatest 

 hourly output was between 7 and 8 A. M. There is no doubt that the 

 minimum excretion is at night. This is probably due to diminished renal 

 activity at night (Hirschstein(&) ), as the uric acid in the blood exhibits no 

 corresponding fluctuations, but possibly to lessened formation of uric acid 

 (Leathes (a), Cathcart, Kennaway, and Leathes). 



The variations in the hourly elimination of uric acid which occur in 

 the fasting individual during the day are due to unknown causes (Neu- 

 wirth). 



The Effect of Purin-containing Food on the Output of Uric Acid. In- 

 gestion of food rich in nucleic acid is followed by an increased excretion 

 of uric acid. This was first clearly shown by Weintraud(a), who observed 

 a uric acid output of 2.5 grams after the feeding of a large quantity of 

 calf thymus (750-1000 grams). Minkowski(e) fed hypoxanthin to men 

 and found that it gave rise to a marked increase in the excretion of uric 

 acid. These observations confirmed by many other workers seemed to prove 

 that the nucleic acid of hypoxanthin and thymus was converted directly 

 into uric acid which was promptly excreted by the kidneys. The uric 

 acid supposedly formed from purins of the food is called the exogenous 

 uric acid while that excreted on a purin-free diet is the endogenous (Bur- 

 ian and Schur(d)). It was maintained that a definite portion, about 50 

 per cent of purin nitrogen of the food, would be excreted as uric acid nitro- 

 gen in the urine of a healthy man. It is now known that no constant per- 

 centage of apurin substance contained in the food reappears in the urine as 



