Fecal immunochemical test
A fecal immunochemical test (FIT) is a test for human hemoglobin in stool as a screening tool for colorectal carcinoma. It is considered a better test than the traditional guaiac fecal occult blood test (gFOBT) which cannot distinguish human blood from food-derived sources.
A fecal immunochemical test uses an antibody-based assay for the globin component of the hemoglobin molecule 2. The laboratory assay employs an automated immunoturbidometric test. Point of care assays use a form of immunochromatography 2.
There are a very large number of fecal immunochemical tests on the market and they are not equivalent in their accuracy 2.
Clearly, depending on the level of fecal hemoglobin used as a cut-off value, the sensitivity and specificity of the fecal immunochemical test will vary.
History and etymology
The guaiac-based test has been in regular clinical use for a very long time, first being developed in the 1860s. Fecal immunochemical tests were introduced in the 1970s 2.
- 1. Amitay EL, Gies A, Weigl K, Brenner H. Fecal Immunochemical Tests for Colorectal Cancer Screening: Is Fecal Sampling from Multiple Sites Necessary?. (2019) Cancers. doi:10.3390/cancers11030400 - Pubmed
- 2. Daly JM, Xu Y, Levy BT. Which Fecal Immunochemical Test Should I Choose?. (2017) Journal of primary care & community health. 8 (4): 264-277. doi:10.1177/2150131917705206 - Pubmed
- 3. Nielson CM, Petrik AF, Jacob L, Vollmer WM, Keast EM, Schneider JL, Rivelli JS, Kapka TJ, Meenan RT, Mummadi RR, Green BB, Coronado GD. Positive predictive values of fecal immunochemical tests used in the STOP CRC pragmatic trial. (2018) Cancer medicine. 7 (9): 4781-4790. doi:10.1002/cam4.1727 - Pubmed