Tests for Glucosuria: An Analysis of Factors That Cause Misleading Results

Abstract

The incidence of potentially erroneous tests for urinary glucose was studied. Each urine specimen collected was tested with Clinitest, Clinistix, Diastix, and Tes-Tape before and after addition of glucose to produce a urine glucose concentration of 1/2 per cent. There was a 23 per cent incidence of falsely high (>1/ 2 per cent) and a 33 per cent incidence of falsely low (<1/2 per cent) results in the 513 specimens examined. Underreading, frequently caused by urinary metabolites of common medications, was seen only with Clinistix and Diastix. Overreading had a distinct relationship to dilute urine and was most frequent with Clinitest (65 per cent). The patient's habits (medications taken and water ingestion) should be considered carefully when a urine testing method is selected. Periodic plasma glucose measurements are recommended to confirm impressions obtained from urine tests for glucose.