Occult Faecal Blood Loss Determined by a ⁵¹Cr Method and Chemical Tests in Patients Referred for Colonoscopy

Abstract

In 67 patients referred for colonoscopy the faecal blood loss was determined by a ⁵¹Cr method and 7 chemical tests. For patients with negative colonoscopy (no. = 10), colorectal polyps (no. = 24), rectal cancer (no. = 8), or colonic cancer (no. = 12), the median ⁵¹Cr-determined faecal blood loss was 0.67, 0.74, 1.26, and 2.18 ml/24 h, respectively. For all chemical tests the results were highly influenced by the upper time limit for a positive reaction. Mixing of faecal specimens before testing proved unimportant. Fecatwin® sensitive showed more positive tests in delayed compared with immediate analyses (p < 0.01). Of cases of colorectal polyps, tetramethylbenzidine (TMB) tests including Hemo-Fec® Test could detect half, the benzidine test 2 of 5, Fecatwin sensitive and Hemoccult® II 1 of 4, and Fecatwin® 1 of 24. Of cases of colorectal cancer, TMB tests, the benzidine test, Fecatwin sensitive, Hemoccult, and Fecatwin could detect about 85%, 85%, 85%, 80%, and 45%, respectively. All chemical tests detected faecal blood loss from colorectal lesions more easily than from gastric lesions.

Key words:

• Benzidine, analysis
• blood, faecal
• chromium radioisotope
• Fecatwin®
• Fecatwin® sensitive
• guaiac, analysis
• Hemoccult® II
• Hemo-Fec® test
• haemorrhage, gastrointestinal
• tetramethylbenzidine, analysis