UlflV ACID !\ Till. lil.Oiil). 77.S',S'L'£,S' AND URINE 627 



concent i';it ion ot' the nrinc, it Ix'conu's iii)i)ar('nt liow totally devoid of 

 significant'C is the presence of crystals of uric acid and urates in the 

 urine, and how falUicious is any theorization based upon the excretion 

 of considerable quantities of uric acid when all the above-mentioned 

 factors, especially the diet, are not controlled and taken into consid- 

 eration. Yet on just such an inade(iuate basis has been constructed 

 an enormous amount of theorization as to "uric-acid diathesis," "uric- 

 acid intoxication," "lithemia, " etc., until it has come to be popularly 

 believed that a larg-e share of the minor ailments of humanity, and in 

 particular all non-infectious diseases of the joints and nuiscles, are 

 dependent u])()n the presence of excessive quantities of uric acid or 

 urates in the blood. But it may be safely stated that at the present 

 time there exists no good evidence which makes it probable that uric 

 acid is responsible for any pathological conditions whatever, except 

 uric-aeid calculi, "uric-acid infarcts" in the kidneys, and certain 

 manifestations of gout. Uric acid is possessed of but a very slight 

 degree of toxicity, and the body is able to get rid of it in such large 

 measure that an actual intoxication with uric acid probably never 

 occurs. 



The amount present in the urine may be very considerably in- 

 creased by eating food rich in purines, of which sweet-breads, liver, 

 and kidney are the best examples ; and also coffee with its caffeine 

 (trimethyl purine), may give rise to a little uric acid, although the 

 methylated purines seem to be destroyed in large part, or eliminated 

 as something else than uric acid. Large quantities of meat will also 

 increase the uric acid, because of the free purines contained in muscle ; 

 and even a diet rich in proteins free from purine will also increase the 

 uric acid excretion over that of a low protein diet.^"' However, the 

 amount of uric acid in the blood is not correspondingly raised, ^'"^'^ this 

 being regulated by the binding function of the tissues, and by excre- 

 tion through the kidneys.^^" According to Folin and Denis ^^ human 

 blood contains 1.5-2.5 mgs. uric acid in 100 cc, and the amount bears 

 no fixt relation to the amount of urea and total non-protein nitrogen 

 of the blood.^*"^ Any difficulty in renal elimination is usually accom- 

 panied by an increase in the amount of uric acid in the blood, in 

 uremia as much as 15 to 20 mg. being sometimes found per 100 c.c.^^" 

 In early interstitial nephritis there may be 4 to 8 mg. of uric acid per 

 100 c.e. blood without a corresponding increase in urea and creatinine, 



15 Taylor and Rose, Jour. Biol. Cliem., .1914 (18), 519. 



I'iaSce Denis. Jour. Riol. Chem., 1915 (23), 147. 



15b Stoeker found \nic. acid in saliva, increased in all conditions associated 

 with uricomia ( Tnau^. Dissert.. Zurich, 1913). 



ifi Jour. Biol. C'heni., WU (14). 29: Arch. Int. Med., 1915 (Ifi). 3:1. 



i'''.i In infants tlic amount is sliylith' lower, about 1.3 to 1.7 mu;. Lii'finann. 

 Zeit. Kinderheilk., 1915 (12). 227.' 



ir.b See Folin and Denis, Arch. Int. :\rcd., 1915 (16), 33; :\revers and Fine, 

 ibid., 1916 (17), 570. 



