What does the guaiac-based fecal occult blood test (gFOBT) identify?

What does the guaiac-based fecal occult blood test (gFOBT) identify?

• A. Hemoglobin by blue color change on reagent-impregnated paper
• B. Tumor DNA mutations
• C. Platelet function
• D. Glucose levels

Answer: (A)

The test is about detecting hidden blood in stool by a color reaction caused by hemoglobin. Guaiac-impregnated paper acts as a substrate; when a stool sample containing hemoglobin is applied and a peroxide developer is added, the heme catalyzes oxidation of the guaiac, turning the paper blue. A blue color indicates occult blood in the stool, reflecting the presence of hemoglobin. This test does not measure DNA mutations, platelet function, or glucose levels, so those options aren’t applicable. It’s used for colorectal cancer screening, though results can be influenced by diet or medications that affect peroxidase activity.

The test is about detecting hidden blood in stool by a color reaction caused by hemoglobin. Guaiac-impregnated paper acts as a substrate; when a stool sample containing hemoglobin is applied and a peroxide developer is added, the heme catalyzes oxidation of the guaiac, turning the paper blue. A blue color indicates occult blood in the stool, reflecting the presence of hemoglobin. This test does not measure DNA mutations, platelet function, or glucose levels, so those options aren’t applicable. It’s used for colorectal cancer screening, though results can be influenced by diet or medications that affect peroxidase activity.