Which enzyme is used to measure glucose in urine strips, and what interference can cause a false positive?

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Multiple Choice

Which enzyme is used to measure glucose in urine strips, and what interference can cause a false positive?

Urine glucose strips detect glucose through an enzymatic color-change reaction. Glucose oxidase catalyzes the oxidation of glucose to gluconic acid, producing hydrogen peroxide as a byproduct. The test then uses a color-developing step that relies on peroxidase to convert a colorless dye into a colored form in the presence of hydrogen peroxide. Because the color change depends on this reaction sequence, any oxidizing substance that can interact with the dye or the peroxidase can create a signal even without glucose. Household bleach is a strong oxidizer, and when present with the peroxidase on the strip, it can drive the color development and cause a false positive—an apparent glucose reading even when glucose isn’t present. The other enzymes listed aren’t used for glucose detection in urine strips: urease measures urea, and lactate dehydrogenase measures lactate, so they wouldn’t produce the glucose-specific color change described. Vitamin C can interfere by reducing the color, typically causing a false negative rather than a false positive.

Urine glucose strips detect glucose through an enzymatic color-change reaction. Glucose oxidase catalyzes the oxidation of glucose to gluconic acid, producing hydrogen peroxide as a byproduct. The test then uses a color-developing step that relies on peroxidase to convert a colorless dye into a colored form in the presence of hydrogen peroxide. Because the color change depends on this reaction sequence, any oxidizing substance that can interact with the dye or the peroxidase can create a signal even without glucose. Household bleach is a strong oxidizer, and when present with the peroxidase on the strip, it can drive the color development and cause a false positive—an apparent glucose reading even when glucose isn’t present. The other enzymes listed aren’t used for glucose detection in urine strips: urease measures urea, and lactate dehydrogenase measures lactate, so they wouldn’t produce the glucose-specific color change described. Vitamin C can interfere by reducing the color, typically causing a false negative rather than a false positive.

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