Wlni \T. COMPOSITION, \M> CHARACTER "l ' RIN 



of the blood. For the latter reason the determination of the ammonia 

 excretion in urine is of some clinical importanc The ingestion of 

 mineral acids increases the ammonia excretion, while alkalies tend to 

 reduce it. During Easting and in diseases such as diabetes, where t! 

 is an abnormal metabolism, the amounl of ammonia in tli" urine is in- 



creased. Ordinarily the dailj outpul of ai nia nitrogen does uol 



exceed 0.5-0.6 gm., constituting 3-5 per cenl of the total amounl of 

 nitrogen. 



Creatinine. — On a meat-free diet the daily excretion o tinine is 



remarkably constant, amounting to from 7 to 11 1 1 1 -_ r . per kilogram of 

 bodj weight. For this reason iu determination is accepted as an in- 

 dispensable feature in metabolism investigations involving urine an- 

 al \ sis. 



Any gross variation from the normal amounl indicates the certain 

 failure of the attendants to colled all of the twenty-four-hour specimen 

 of urine. Normally the blood contains from 1 to 2 mg. per LOO e 



The creatinine is one of the last of the urinary constituents to accumu- 

 late in the blood during renal insufficiency, and for this >n affords 

 a reliable prognostic indication concerning the patients' condition. A 



rise in the creatinine concentration of the l»l 1 is eviden E serious 



renal disease, patients with concentrations of 5 mg. never i ring 



(Chase and Meyers : The concentration of creatinine in tin- urine is 

 aboul H»» times greater than in the bl 1. 



In adult man creatine does no1 appear in the urine save during starva- 

 tion or wasting diseases. In woman it is absenl save after postpartum 



olution of the uterus. Children commonly excrete creatine al< - 

 with creatinine until the middle years of childl I. 



The Purine Bodies and Uric Acid. The mosl important purine in 

 human urine is uric acid. Xanthine is the nexl in importance, and small 

 amounts of hypoxanthine, guanine, and adenine are found. Among the 

 mosl interesting of the salts of the urine to the clinician are the un 

 because an accumulation of uric acid in the body was believed to be 

 responsible for many obscure clinical conditions. It is quite true that 

 tlif salts of uric acid arc found iii higher than normal amounl in some 

 .lis. especially gout, leukemia, and chronic nephritis, but the many 



vague theories associated with uric acid and disease ha^ ago ' 



exploded. 



The human body has the almost unique distinction among mammals 

 of not being able to destroy anj of the uric acid it produces, and h< 

 all the uric acid formed during metabolism must b< I in the urine 



Unfortunately the kidney appears to be less competi rid the body 



of this wast.- than it is of the other urinan metabolites, a the 



