Enzyme immunoassay for occult faecal blood

The specificity and sensitivity of immuno-assays can be usefully exploited for early detection of digestive bleeding disorders. We have developed an enzyme immuno-assay (EIA) specific of human haemoglobin (Hb-Hu) by which occult faecal blood can be detected without any need for dietary restrictions or for repetitive sampling, as would be required with other procedures. This EIA can detect Hb-Hu by a sensitivity of 2.5 ng/ml of faecal extract as well as dissociated alpha and beta chains and peptic or tryptic proteolytic Hb-Hu fragments. The EIA, when applied to occult faecal bleeding in patients with malignant tumours in the digestive system, was positive on some 80 percent of all samples.