Which screening test uses a guaiac-based method to detect occult blood in stool?

Which screening test uses a guaiac-based method to detect occult blood in stool?

• A. Guaiac-based fecal occult blood test (gFOBT)
• B. Fecal immunochemical test (FIT)
• C. Multitarget stool DNA test
• D. Colonoscopy

Answer: (A)

The test described uses a guaiac reagent to detect occult blood by leveraging the peroxidase activity of heme. In practice, stool is applied to a guaiac-coated card and, when a developer (often hydrogen peroxide) is added, the heme in any blood in the sample catalyzes a reaction that turns the guaiac blue. That color change indicates the presence of occult blood. This chemical, guaiac-based approach is distinct from immunochemical methods that use antibodies against human hemoglobin, and it differs from tests that detect DNA markers or are done via colonoscopy. The guaiac method is sensitive to factors like diet or certain medications that can cause false results, which is an important consideration in interpreting the test.

The test described uses a guaiac reagent to detect occult blood by leveraging the peroxidase activity of heme. In practice, stool is applied to a guaiac-coated card and, when a developer (often hydrogen peroxide) is added, the heme in any blood in the sample catalyzes a reaction that turns the guaiac blue. That color change indicates the presence of occult blood. This chemical, guaiac-based approach is distinct from immunochemical methods that use antibodies against human hemoglobin, and it differs from tests that detect DNA markers or are done via colonoscopy. The guaiac method is sensitive to factors like diet or certain medications that can cause false results, which is an important consideration in interpreting the test.