541 



On the Relation between the Output of Uric Acid and the Rate of 



Heat Production in the Body. 



By E. P. Cathcart, M.D., and J. B. Leathes, M.B. 



(Communicated by Dr. C. J. Martin, F.RS. Eeceived June 22, — Bead 



June 27, 1907.) 



(From the Lister Institute of Preventive Medicine.) 



The rate at which uric acid is turned out of the body is very different at 

 different times of the day, even when the food contains no ready-made 

 purine derivatives. It is higher during the early hours of the day than at 

 any time, and it is considerably lower at night. The reason for this, as 

 was pointed out by one of us,* is not likely to be that the excretory 

 functions are depressed at night, since these functions, to judge from the 

 total nitrogen of the urine, are more active during the first hours of sleep 

 than at any time in the 24 hours. And since, when the diet is confined 

 to bread, butter, and milk, the uric acid must be derived from the body 

 substance and not from the food, it seems probable that there is some 

 function of the body which is in abeyance during sleep and is, to a consider- 

 able degree, responsible for the output of uric acid ; some function, that 

 is to say, which is effected by chemical reactions involving the production 

 of uric acid, and of nothing else that can be detected in the urine, unless it 

 be phosphoric acid, and possibly in some measure creatinine. 



If it is possible to identify this function, the activity of which can, on 

 a suitable diet, be measured by the amount of uric acid excreted, it may 

 be possible to give a clearer account of the processes by which, at the onset 

 of fever, the temperature of the body can be sent up independently of any 

 voluntary muscular activity ; for while the temperature is rising, the output 

 of uric acid may be four times as great as it otherwise would be.f Similarly, 

 in the study of other pathological conditions in which uric acid plays a part, 

 it must be of importance to be able to point to the kind of activity which 

 is accompanied by increased uric acid production. 



The following series of observations, which we have worked out con- 

 jointly, was designed to show how the reaction of the body to loss of heat 

 on the one hand, and the heat produced by ordinary muscular exertions 

 on the other, might affect the amount of uric acid in the urine. It was 

 the outcome of several earlier, as yet unpublished, experiments, which 



* J. B. Leathes, ' Journal of Physiology,' vol. 35, p. 125, 1906. 

 t Loc. vit., p. 205. 



