Free hemoglobin is immediately complexed with the serum protein haptoglobin. The hemoglobin-haptoglobin complex is more stable during the long intestinal passage than hemoglobin alone. Even bleeding adenomas/carcinomas of the upper gastrointestinal tract can be detected. The combined use of both ELISA tests (hemoglobin and hemoglobin/haptoglobin complex) enables the early detection of colorectal carcinomas with the highest sensitivity.

This immunological test for quantitative measurement of the Hb-Hp-complex in stool is able to detect low concentrations of the hemoglobin-haptoglobin-complex in feces. First clinical data show a good ability of the test to detect colorectal carcinomas in early stages as well as polyps of the colon and rectum.