Comparison of gastrointestinal bleeding markers used in fecal occult blood testing

Abstract

We measured blood proteins in feces to examine their usefulness in fecal occult blood testing. The antigenicity of hemoglobin (Hb) in feces was most unstable in the protein that we measured. The quantity of transferrin (Tf) as an indicator of blood volume was 5 times that of Hb in feces from colon cancer patients, and Tf was more stable than Hb as a bleeding marker. The detection of alpha 1 acidglycoprotein (AG) showed not only a quantity of blood equivalency 20 times higher than that of Hb in feces from colon cancer patients, but also a high rate of detection in stomach cancer patients. It was thought that AG is a useful bleeding marker capable of demonstrating bleeding from the whole gastrointestinal tract. Alpha-1 antitrypsin was found to be highly dense in feces, but was not a specific bleeding marker. Because the antigenicity of Hb is easily lost during Hb measurement as a screening test for colon cancer, false positives as well as false negatives can easily occur. However, such problems may be addressed by utilizing different bleeding markers.