The superiority of enzyme impregnated paper for determining glycosuria in patients receiving antituberculosis drug therapy.

Qualitative and quantitative analysis of the urine for glucose is gener ’ .ly accepted as a useful measure for the detection of diabetics and for ihe daily follow up of those with proved diabetes as a rough practical estimation of the degree of control of blood sugar levels. In the past the test :ommonly employed using Benedict’s Solution depended on the fact that cupric sulfate was reduced in the presence of glucose in the urine to cuprous oxide, an insoluble yellow or red precipitate. More convenient tablets such as “Clinitest” utilize the same principle of copper reduction. It has been known that reducing substances, other than glucose will at times give a false-positive test in the urine using copper reduction method, but generally these instances were infrequently encountered clinically. In addition there has, in the past, been no simple specific test for urine glucose available, so that to prove by further identification that the reducing substance in the urine was actually glucose involved such procedures as paper chromatography, fermentation tests or the osazone test, none of which is particularly adaptable for bedside use.’ Recently the development of a testing paper impregnated with the enzyme, glucose-oxidase, has made available a simple specific test for glucose in the urine.* The enzyme, glucose-oxidase, reacts with glucose to form hydrogen peroxide and gluconic acid. The hydrogen peroxide then reacts with peroxidase and orthotolidine, also impregnated in the paper, to form a light green to blue-black color depending on the concentration of glucose present in the urine. The present study is submitted to call attention to a clinical situation in which the presence of reducing substances in the urine other than glucose is a relatively common occurrence, namely, in patients receiving antituberculosis drug therapy, and the usefulness of the enzyme impregnated test paper under these circumstances as a test for glycosuria. A survey was made on the tuberculosis service of the Providence Veterans Administration Hospital for the incidence of false-positive tests for glucose in the urine using the copper reduction method. Of 40 patients receiving antituberculosis drugs, 30 (75 per cent) were founO to have false-positive tests for glycosuria with the copper reduction Benedict’s test, varying from trace to two plus. None had false-positive tests with the specific enzyme impregnated paper. Blood sugar determinations in the fasting and postprandial states (11 a.m.) were carried out on each patient, all of which were normal. The results are shown in Table I. Interference of antituberculosis drugs in the testing of urine for glucose with the copper reduction methods has been noted in other studies.