Which of the following is NOT listed as a common interference in Trinder-type glucose assays?

• A. Hemoglobin
• B. Ascorbic acid
• C. Bilirubin
• D. Cholesterol

Answer: (D)

In Trinder-type glucose assays, glucose is measured through an enzymatic reaction that ultimately produces a colored signal. The strength of this color is read spectrophotometrically and is proportional to glucose concentration. Substances that alter the color signal or the light absorption at the assay wavelength can skew the result, so they’re considered interferences.

Hemoglobin affects the readout because its red color absorbs light in the same region used to detect the color change, leading to inaccurate measurements. Bilirubin, with its yellow-orange hue, can also absorb light and interfere with the color signal, especially in icteric samples. Ascorbic acid (vitamin C) can act as a reducing agent and diminish the color development by quenching the oxidized chromogen or consuming the reactive peroxide, giving falsely low readings.

Cholesterol itself is not typically listed as a direct interference in these Trinder-type glucose assays. Lipemia or turbidity from high lipid content can affect the measurement, but cholesterol per se isn’t considered a common interfering substance in the standard interference lists.