Occult blood testing using tetramethylbenzidine in an extraction procedure for patients on unrestricted diets

Area of Science:

• Clinical Chemistry
• Gastroenterology
• Diagnostic Assays

Background:

• Fecal occult blood testing is crucial for diagnosing gastrointestinal disorders.
• Conventional slide tests can be affected by dietary factors and other substances.
• There is a need for more reliable and specific stool occult blood tests.

Purpose of the Study:

• To develop and evaluate a novel extraction test for stool occult blood detection.
• To assess the test's reliability in the presence of common interfering substances.
• To compare the performance of the new test against conventional slide tests.

Main Methods:

• Development of an extraction test utilizing 3,3',5,5' tetramethylbenzidine (TMB).
• Application of the TMB-based extraction test to 1,320 fecal specimens.
• Comparison of results with commercial slide tests, considering dietary intake (e.g., vitamin C).

Main Results:

• The TMB extraction test demonstrated reliability with interfering substances like vitamin C, meat, and enzymes.
• Discrepancies were observed between the extraction test and slide tests, with some slide-positive samples being negative by extraction.
• The extraction test identified positive results in specimens that were equivocal or negative by slide tests, including one from a patient not taking vitamin C.

Conclusions:

• The developed TMB extraction test offers improved specificity and reliability for stool occult blood detection.
• This method potentially reduces false positives and negatives associated with conventional slide tests.
• The test shows promise for more accurate screening and diagnosis of gastrointestinal bleeding.