URINE 415 



prevent bumping) and boil with constant shaking 1 for one and one-half minutes 

 If the sugar present is considerable (above the normal variations), a typical reduc- 

 tion is obtained. If the trace of sugar is smaller, but still rather large, the whole 

 solution will become turbid as in Benedict's test. If no such turbidity is produced 

 and the boiling mixture remains clear, transfer it at once (i.e., while still very hot) 

 to centrifuge tube and centrifuge for one to two minutes. Typical red cuprous 

 oxide such as is obtained with pure sugar solutions will be found in the bottom of the 

 centrifuge tube below the green crystalline potassium picrate which usually forms 

 as the liquid cools. 



Some copper reagents made as described above give a slight cuprous oxide 

 sediment when boiled alone, i.e., without any added sugar or urine. When that is 

 the case the reagent must be boiled and centrifuged once before using it for the test. 



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 

 diabetes, fevers, and in certain hepatic diseases in which the parenchyma 

 of the liver is seriously affected. Under other pathological conditions 

 the output may be diminished. These variations, however, in the 

 excretion of the volatile fatty acids possess very little diagnostic 

 value. 



CH 3 



PARALACTIC ACID, CH(OH) 



COOH. 



1 The shaking is desirable to avoid bumping and is necessary to prevent superheating 

 and consequent reduction of the reagent on the sides of the test tube. 



