URINE 413 



GLUCOSE 



Traces of this sugar occur in normal urine, but the amount is not 

 sufficient to be readily detected by the ordinary simple qualitative 

 tests. There are two distinct types of pathological glycosuria, i.e, 

 transitory glycosuria and persistent glycosuria. The transitory type 

 may follow the ingestion of an excess of sugar, causing the assimilation 

 limit to be exceeded, or it may accompany any one of several disorders 

 which cause impairment of the power of assimilating sugar. In the 

 persistent type large amounts of sugar are excreted daily in the urine 

 for long periods of time. Under such circumstances a condition known 

 as diabetes mellitus exists. In this disorder the urine may contain 10 

 per cent of glucose and the average sugar content is 3-5 per cent. 

 Ordinarily, diabetic urine which contains a high percentage of sugar 

 possesses a faint yellow color, a high specific gravity, and a volume 

 which is above normal. Over 100 grams of sugar are daily eliminated 

 in some severe cases of diabetes mellitus. 



EXPERIMENTS 



The various tests for glucose in the urine which are embraced in the 

 experiments given herewith are based upon one of the following 

 properties of this sugar: 



(1) Its power to reduce the oxides of certain metals in alkaline solution. 



(2) Its power to rotate the plane of polarized light. 



(3) Its power to form crystalline osazones with phenylhydrazine. 



(4) Its ability to ferment with ordinary yeast. 



i. Phenylhydrazine Reaction. Test the urine according to one of the fol- 

 lowing methods : (a) To a small amount of phenylhydrazine mixture (enough to 

 fill the rounded portion of a small test-tube), furnished by the instructor, 1 add 

 5 c.c. of the urine, shake well, and heat on a boiling water-bath for one-half to 

 three-quarters of an hour. Allow the tube to cool slowly (not under the tap) and 

 examine the crystals microscopically (Plate III, opposite page 22). If the solu- 

 tion has become too concentrated in the boiling process it will be light red in color 

 and no crystals will separate until it is diluted with water. 



Yellow crystalline bodies called osazones are formed from certain 

 sugars under these conditions, in general each individual sugar giving 

 rise to an osazone of a definite crystalline form which is typical for that 

 sugar. 



It is important to remember in this connection that, of the simple 

 sugars of interest in physiological chemistry, glucose and fructose yield 

 the same osazone, with phenylhydrazine. Each ozazone has a definite 



1 This mixture is prepared by combining one part of phenylhydrazine-hydrochloride and 

 two parts of sodium acetate, by weight. These are thoroughly mixed in a mortar. 



