Faecal occult blood testing
The test
- Detects occult blood in stool as a surrogate for colorectal neoplasia
- *iFOBT (faecal immunochemical test, FIT) has replaced the older guaiac test (gFOBT)*
| iFOBT / FIT | gFOBT (obsolete) | |
|---|---|---|
| Detects | Human globin antibody-based | Haem peroxidase activity |
| Specificity | High - human blood only | Low |
| Dietary/drug restriction | None needed | Red meat, peroxidase-rich vegetables, vitamin C |
| Upper GI blood | Not detected (globin digested) - a feature, not a flaw | Detected |
| Quantitative | Yes - threshold adjustable | No |
8 more sections, plus exam facts
Premium unlocks every note across every specialty, and the full exam fact library behind it.
Get premium access