A false-positive urinary glucose result can be observed if:

Question

Quizplus · Accepted Answer

Because reagent strip tests are all specific for glucose,most interferences lead to reduced or false-negative results.
 False-positive results
·Contamination by bleach or other strong oxidizing agents may oxidize the reduced form of the dye present on the reagent strip,causing a color change in the absence of glucose.This shows the importance of using contamination-free urine containers and work surfaces.
·Trace values may be seen in very dilute urine specimens because of increased sensitivity at low-specific gravity.
·Reagent strips exposed to air by improper storage have been shown to give false-positive results.
 False-negative or delayed results
·Large urinary concentrations of ascorbic acid,from therapeutic doses of vitamin C or from drugs,such as tetracyclines,in which ascorbic acid is used as a reducing agent.Ascorbic acid blocks or delays the reaction by acting as a reducing agent reacting with the released hydrogen peroxide (rather than the chromogen in the reagent strip).Multistix products are inhibited by ascorbic acid concentrations of 50 mg/dL (500 mg/L)or greater in specimens containing small amounts (75 to 125 mg/dL)of glucose.Chemstrip is unaffected by ascorbic acid concentration less than 100 mg/dL (1000 mg/L).
·With questionable ascorbic acid interference,repeat tests on urine voided at least 10 hours after the last administration of vitamin C,or test for ascorbic acid.
·Ketone bodies at moderate levels (=40 mg/dL)in specimens containing small amounts (75 to 125 mg/dL)of glucose.This combination of high ketone and low glucose is unlikely in a patient with diabetes.
·Sodium fluoride is an enzyme inhibitor.Do not use as a preservative.
·Refrigerated specimens,because of decreased enzyme activity.Urine must be at room temperature when tested.

A False-Positive Urinary Glucose Result Can Be Observed If