298 ISIDOR GREENWALD 



identical. Therefore, it is important that the test be controlled by a 

 similar test with normal urine containing added glucose. 



Occurrence. If the voluminous literature on the subject of the oc- 

 currence of fructose in diabetic urines be reviewed, it will be found that 

 few reports will stand critical examination. In most of those in which 

 the evidence at first seems strongest the urine contained five per cent, or 

 more, of glucose. In none of these can the tests applied be considered to 

 have been properly controlled, so that the actual presence of fructose may 

 well be doubted. Moreover, in the light of what we now know of the 

 ready conversion of glucose into fructose in the presence of weak alkalies 

 (Lobry de Bruyn and van Ekenstein), the small amount of fructose re- 

 ported may have, in some cases at least, been formed after the secretion 

 of the urine. 



There remain, however, a number of cases in which the presence of 

 fructose may be regarded as established. With few exceptions, these are 

 cases of pure fructosuria, only the one sugar appearing in the urine. 

 These include those reported by Seegen (also by Kiilz), Rosin and Laband, 

 Schlesinger, Lepine and Boulud(6), Neubauer(a), von Moraczewski(fr), 

 Borchardt(6), Adler(&), and by Strouse and Friedman. In addition, 

 there are a number of cases such as that reported by Czapek(fr) and 

 by Zimmer (a), and others by May, Lion and others, in which the presence 

 of fructose is indicated but in which the identity of the levorotatory sub- 

 stance was not satisfactorily established. 



One of the most interesting of these doubtful cases is that of Czapek 

 and of Zimmer. The patient was a military surgeon, twenty-nine years 

 old, who had had an attack of icterus eleven years previously. When first 

 observed, he was excreting 2,500 to 3,000 c.c. of urine a day, with a 

 sugar content, determined by titration, of 2.5 to 3 per cent. Later, even 

 on a strict diet, this rose to 10 per cent, with a total excretion of four or 

 five liters a day. After a course of treatment at Carlsbad, the volume 

 of urine dropped to 1,500 c.c. and the sugar content to one per cent. In 

 spite of the high reducing power, both Czapek and Zimmer found the 

 urine to be levorotatory. There can be little question here of errors 

 inherent in the analytical procedure, for Czapek expressly states that an 

 acid urine containing 6.6 per cent of glucose by titration with Fehling's 

 solution was cleared by the addition of a little powdered neutral lead 

 acetate and then showed a rotation of 1 per cent. If the presence of 

 (3-hydroxybutyric acid be held responsible, the required concentration 

 would be 16 per cent and, in some other specimens, even more. It would 

 seem that this was really a case of diabetes complicated by fructosuria. 



Apart from its possible occurrence in diabetes, fructosuria is a rather 

 rare condition. In the series of examinations at Carlsbad, already alluded 

 to in the discussion of pentosuria, Adler found only two cases of 

 fructosuria in 7,726 urines, 1,490 of which reduced Fehling's solution. 



