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A 34-year-old member asked:

What is the principle behind the occult blood test?

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Dr. Gurmukh Singh
Pathology 49 years experience
More than one: Guaiac test measures peroxidase activity which is associated with blood from any site in the GI tract, including blood in meats, and peroxidase in horse raddish. A different test measure human globin part of hemoglobin and detects only blood originating in the large intestine.
Dr. Charles Cattano
Gastroenterology 39 years experience
FIT or hemoccult?: If you're using the old hemoccult slide, you'll notice its two-sided. Place your specimen on one side, close the lid. Doctor or lab, when developing your specimen, turns the card over, opens the back & applies the developer solution which soaks thru to your specimen. A color change indicates your specimen contains invisible blood. Principle & mechanics differ with FIT (fecal immunochemical test).

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Last updated Feb 9, 2015
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