Rapid immunochemical detection of fecal occult blood by use of a latex-agglutination test.

A novel immunochemical test, "Hemolex," is characterized and compared with three guaiac tests: "Hemoccult" (Smith-Kline, U.S.A.), "Hemofec" (Boehringer Mannheim, F.R.G.), and "Fecatwin Sensitive" (Labsystems, Finland). We tested 191 stool specimens from patients, 144 from healthy persons. The sensitivity of Hemolex was 0.6 mL of blood per 100 g of stool. It reacts with neither animal hemoglobin nor human myoglobin, unlike the guaiac tests, nor does it react with the stool of healthy persons under no dietary restrictions, while the guaiac tests react variably. As a rule, Hemolex is insensitive to bleeding in the upper gastrointestinal tract, unlike the guaiac tests. However, Hemolex seems to be more sensitive to bleeding in the lower gastrointestinal canal than are the other tests, and we show it to be suitable for screening for occult blood originating there. It is unaffected by diet. It is simple to perform, requires no special equipment, and stool specimens, stored in the test diluent, are stable for testing for two weeks.