Which enzymatic creatinine method uses creatininase with peroxidase (POD) as part of the coupled reaction?

• A. Creatininase-POD coupled
• B. Creatininase-CK coupled
• C. Creatininase alone
• D. POD-only test

Answer: (A)

Enzymatic creatinine assays rely on a linked enzyme system that finally produces a color signal proportional to the amount of creatinine present. Creatininase initiates the sequence by converting creatinine to creatine. In the coupled format, the downstream reactions generate hydrogen peroxide, which peroxidase uses to oxidize a chromogenic substrate and create a measurable color. That coupling of creatininase with peroxidase is why this method is the correct choice: it directly ties the initial creatinine processing to the color development step through the POD reaction. Using creatininase with creatine kinase would involve a different metabolic step not used in this colorimetric creatinine assay, while creatininase alone cannot yield a color signal without the peroxidase-driven chromogen reaction, and a POD-only test cannot process creatinine without the enzymatic conversion upstream.