Clinical Identification and Measurement of Urinary Sugars

Abstract

In the routine urinalysis of the Prudential Laboratory all copper-reducing urines have for some years been measured by our modification 1 of Sumner's 2 di-nitro-salicylic acid method. Because of its speed, accuracy and independence of personal equations of technicians we use the Photo-Electric Scopometer, 3 but the method also works well with Junior Scopometer, 4 colorimeter or even permanent test tube standards.∗

After Lasker and Enklewitz 5 drew attention to the fact that urines containing keto-pentose reduce Benedict's qualitative copper reagent at room temperature, we observed that ketose-containing urines also reduced our di-nitro-salicylic acid reagent at room temperature, perhaps more perceptibly than they do copper. When the reductions of di-nitro-salicylic acid by keto-pentose at room temperature were measured and the tests then boiled and the total reductions measured in our usual way, the results proved very consistent. We therefore began placing all di-nitro-salicylic acid tests in a water bath at 30° for 5 minutes and measuring whatever reduction might occur before going on in our usual way to boil the tests and measure the total reduction.

One result of this new step was the discovery of more pentose-containing urines than were hitherto seen. Another result was the finding of a constant proportionality between the ketose reduced at the lower temperature and the total ketose reduced by boiling: a relationship which seems to hold regardless of the concentration of ketose in the specimen.

This information, coupled with observations made in the course of previous experiments with other sugars and reagents, led us to inquire how urinary sugars other than ketose would behave under the same or similar conditions such as picric acid reductions, etc. The results of some of these studies are shown in Fig. 1, and similar results may, of course, be had with temperature constant and time variable.