title: Detection of colorectal neoplasms by the highly sensitive hemoglobin-haptoglobin complex in feces.
abstract: Screening for fecal occult blood by means of guaiac tests has an unsatisfactory sensitivity for the detection of colorectal neoplasms. The immunological determination of human hemoglobin in feces has a higher sensitivity and specificity, but hemoglobin is degraded during its transport through the gastrointestinal tract. We compared the hemoglobin test to a newly developed immuno-chemiluminometric (ILMA) assay for quantifying the hemoglobin-haptoglobin complex in feces which shows high stability against degradation. From each of 621 patients with gastrointestinal complaints before scheduled colonoscopy we collected two 1-ml samples from a single stool; there were no dietary restrictions. The sensitivity for detecting colorectal carcinomas proved 87% with hemoglobin. With the hemoglobin-haptoglobin complex it was 87% at a cutoff level of 1.5 microg/g feces, 83% at 2.0 microg/g feces, and 78% at 2.5 and 3.0 microg/g feces. The sensitivity for detecting large adenomatous polyps was 54% with hemoglobin, 76% with the hemoglobin-haptoglobin complex at a cutoff point of 1.5 microg/g feces, 73% with the hemoglobin-haptoglobin complex at 2.0 and 2.5 microg/g feces, and 65% with the hemoglobin-haptoglobin complex at 3.0 microg/g feces. The optimal cutoff point for the hemoglobin-haptoglobin complex was estimated to be 2.0 microg/g stool. The specificity for hemoglobin (99%) was significantly higher than that for the hemoglobin-haptoglobin complex at 2.0 microg/g feces (96%). Immunological determination of the hemoglobin-haptoglobin complex in feces has a comparable sensitivity as the fecal hemoglobin assay for colorectal carcinomas and a significantly higher sensitivity for adenomatous polyps but a significantly lower specificity. Its use for colorectal cancer prevention is currently being evaluated in a screening study.
authors.affiliation: Practice of Gastroenterology, Hauptstrasse 45, D-76684 Ostringen, Germany. dr.andreas.sieg@t-online.de
authors.forename: A
authors.initials: A
authors.lastname: Sieg
authors.forename: C
authors.initials: C
authors.lastname: Thoms
authors.forename: K
authors.initials: K
authors.lastname: Lüthgens
authors.forename: M R
authors.initials: MR
authors.lastname: John
authors.forename: H
authors.initials: H
authors.lastname: Schmidt-Gayk
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000175:diagnosis*; D005243:Feces / Q000737:chemistry; D005260:Female; D006242:Haptoglobins / Q000032:analysis*; D006454:Hemoglobins / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009780:Occult Blood; D012680:Sensitivity and Specificity
chemical_list: D006242:Haptoglobins; D006454:Hemoglobins; C035492:haptoglobin-hemoglobin complex