Glucose in normal urine

IN spite of considerable investigation, the question whether small amounts of glucose may occur in normal urine has not yet been satisfactorily answered.The present state of indecision is partly due to the absence of a specific test for this sugar and partly to the fact that it normally occurs in very small quantities.Apart from reduction tests the detection of glucose has generally been based on (1) fermentation with yeast, and (2) the phenylhydrazine reaction.That the reaction is not specific for glucose is not the only drawback as far as yeast fermentation is concerned, for yeast [von Lipmann, 1904] fails, sometimes, to ferment sugar when the concentration of the latter is as low as 0.1 g. per 100 cc.During the present investigation this observation was confirmed.It was possible to obtain glucosazone from urines to which 0.1 g. glucose per 100 cc. had been added even after 3 days' incubation at 370 with a pure yeast culture [see also Patterson, 1926].Objections have often been raised against the use of yeast for the detection of glucose in normal urine.The laborious technique, which the use of pure cultures of yeast necessitates, has unfortunately led to the employment of ordinary yeast instead.This practice has no doubt weakened the evidence for the existence of glucose, though in the majority of urines thus treated fer- mentation did occur [Benedict and his co-workers, 1918; Sumner, 1921; Neuwirth, 1922].But, as has frequently been suggested, such fermentation might be due to the bacteria introduced with the yeast.To attempt to inhibit bacterial growth by making the urine slightly acid or by adding a little volatile antiseptic like toluene is of doubtful value especially if, as is customary, fermentation with ordinary yeast is allowed to go on for 17 to 24 hours or more.In spite of starting with a PH varying between 5-5 and 6*8, Host [1923] found that some of the urines undergoing fermentation with ordinary yeast became strongly ammoniacal.Much reliance cannot, therefore, be placed on positive evidence obtained in experiments with yeast if bacteria were present.The osazone reaction properly carried out is free from such serious draw- backs, and it may, therefore, be expected to furnish more reliabfe information regarding the question of glucose in normal urine.As has been pointed out