Overview: Fecal Immunochemical Quantitative (FIT Quant) TestIntroduction: The Fecal Immunochemical Quantitative (FIT Quant) Test measures blood in stool to screen for colorectal cancer, causing abdominal pain or weight loss. Following 2023 ACS guidelines, it uses an immunoassay for high sensitivity, aiding in cancer screening. This test is critical for guiding diagnosis, treatment, and improving outcomes in immunology for patients with suspected colorectal cancer.
Other Names: FIT Quant Assay, Quantitative Fecal Occult Blood Test.
FDA Status: Laboratory-developed test (LDT), meeting immunology standards for diagnostic accuracy.
Historical Milestone: Fecal occult blood testing began in the 1960s with cancer screening research. Quantitative FIT emerged in the 2000s, improving accuracy for colorectal cancer detection.
Purpose: Screens for colorectal cancer, guides diagnostic evaluation, and monitors fecal hemoglobin in patients with abdominal pain or weight loss.
Test Parameters: 1. Fecal Immunochemical Test
Pretest Condition: Fasting for 10-12 hours required to stabilize results. Collect stool at any time. Report symptoms like abdominal pain or weight loss, and list medications.
Specimen: 5-10 g stool (sterile container). Transport in a biohazard bag within 2 hours.
Sample Stability at Room Temperature: 2 hours
Sample Stability at Refrigeration: 24 hours
Sample Stability at Frozen: Not frozen
Medical History: Document abdominal pain, weight loss, or history of colorectal cancer. Include current medications, especially NSAIDs or anticoagulants.
Consent: Written consent required, detailing the tests purpose, diagnostic implications, and potential need for colonoscopy or cancer therapy.
Procedural Considerations: Uses an immunoassay to quantify fecal hemoglobin levels. Results are available in 1-2 days, enabling rapid clinical decisions.
Factors Affecting Result Accuracy: Non-fasting, dietary factors, or medications can affect results. Non-cancer bleeding may elevate levels.
Clinical Significance: Elevated fecal hemoglobin suggests colorectal cancer, prompting colonoscopy. Normal levels may require repeat testing.
Specialist Consultation: Consult a gastroenterologist or oncologist for result interpretation.
Additional Supporting Tests: Colonoscopy, CEA, or imaging to confirm colorectal cancer.
Test Limitations: Non-specific bleeding may cause false positives. Results require clinical correlation.
References: ACS Colorectal Cancer Guidelines, 2023; CA: A Cancer Journal for Clinicians, Wolf AMD, 2022.
