A patient has a urine uric acid level of 1575 mg/day. What effect will this have on the measured urine glucose level when the glucose oxidase/peroxidase method is employed?

• A. Urine glucose level will be falsely low.
• B. Urine glucose level will be falsely high.
• C. Urine glucose level will be accurate.
• D. Urine glucose level will exceed the linearity of the method.

Answer: (A)

High uric acid in urine can interfere with the glucose oxidase/peroxidase colorimetric assay. In this method, glucose is converted to hydrogen peroxide, and then a peroxidase reaction uses that hydrogen peroxide to produce a colored signal proportional to glucose. Uric acid can react with hydrogen peroxide or the reactive intermediates, scavenging hydrogen peroxide and dampening the color development. This reduces the color intensity and makes the measured glucose appear lower than its true value. So, the presence of high uric acid leads to a falsely low urine glucose result, rather than an accurate reading or a falsely high result.