What it measures
FIT (faecal immunochemical test) looks for tiny amounts of human blood in a sample of poo, too small to see. It uses antibodies that react with human haemoglobin, so food in the diet does not affect it. The result is the amount of haemoglobin found per gram of stool.
Why people test it
- Used in the NHS bowel cancer screening programme for people in the invited age range.
- Used by GPs to help decide whether bowel symptoms need a hospital referral.
- Chosen privately by people outside the screening ages or between screening kits.
Typical range
Results are given in micrograms of haemoglobin per gram of stool. The cut-off for a positive result depends on the lab and the reason for the test, and the report shows which applies.
Finger-prick or vein?
This is not a blood test. A small sample of poo is collected at home on a stick, sealed in a tube and posted to the lab.