URINE 397 



passages. It is probably slightly soluble in the urine. Some investiga- 

 tors believe that the body forming the nubecula of normal urine is 

 nucleoprotein and not a mucin or mucoid as stated above. A discussion 

 of nucleoprotein and related bodies occurring in the urine under patho- 

 logical conditions will be found on page 428. 



NH CO 



I 



OXALUR1C ACID, CO 



I 



NH 2 COOH. 



Oxaluric acid is not a constant constituent of normal human urine, 

 and when found occurs only in traces as the ammonium salt. Upon 

 boiling oxaluric acid it splits into oxalic acid and urea. 



GLUCOSE 



This sugar occurs in traces in normal urine. It is, however, not 

 present in sufficient concentration to be detected by any of the ordinary 

 tests -used in urine analysis. In certain pathological conditions (pp. 

 413 and 523) the sugar in the urine is notably increased. Folin has 

 recently modified Benedict's sugar test (see Chapter XXIII) so it may 

 be used to demonstrate the sugar content of normal urine. 1 



ENZYMES 



Various types of enzymes produced within the organism are excreted 

 in both the feces and the urine. In this connection it is interesting to 

 note that pepsin, rennin, lipase and an amylase have been positively 

 identified in the urine. The occurrence of trypsin in the urine, at least 

 under normal conditions, is questioned. 



VOLATILE FATTY ACIDS 



Acetic, butyric, and formic acids have been found under normal 

 conditions in the urine of man and of certain carnivora as well as in the 

 urine of herbivora. Normally they arise principally from the fermenta- 

 tion of carbohydrates and the putrefaction of proteins. The acids con- 

 taining the fewest carbon atoms (formic and acetic) are found to be 

 present in larger percentage than those which contain a larger number of 

 such atoms. The volatile fatty acids occur in normal urine in traces, 

 the total output for 24 hours according to older investigators varying 

 from 0.008 gram to 0.05 gram. 



Pathologically, the excretion of volatile fatty acids is increased in 



1 Folin: Jour. Biol. Chem. } 22, 327, 1915. 



