saudigastro.com/patients/stool-tests-calprotectin
Results
Calprotectin and blood tests are often reported within a few days. Cultures may take two to several days and some tests for parasites take longer. Your doctor will explain what the result means and whether a colonoscopy, scan or treatment is needed.
This article is educational and does not replace your doctor's advice. Seek urgent care for any red-flag symptoms.
What is it?
Stool (faeces) carries clues about what is happening in the gut. You collect a small sample at home or in the clinic, and the laboratory runs one or more tests. Faecal calprotectin measures a protein released by white blood cells when the bowel lining is inflamed, so a high level suggests inflammation, as in Crohn’s disease or ulcerative colitis, rather than a functional problem such as irritable bowel syndrome. Faecal occult blood tests (including the faecal immunochemical test, FIT) detect tiny amounts of blood that cannot be seen by eye. Stool culture and related tests look for infection by bacteria, parasites or other germs, and may include a test for Clostridioides difficile (C. difficile), a germ that causes severe diarrhoea, often after antibiotics.
Why is it done?
These tests are used to tell inflammatory bowel disease from irritable bowel syndrome, to decide who needs a colonoscopy, to track disease activity and treatment response in people with known inflammatory bowel disease (IBD), to look for the cause of diarrhoea, and as part of screening for bowel cancer (FIT). Each answers a different question, and none gives a final diagnosis on its own.
Who needs it?
- People with long-lasting diarrhoea, belly pain or weight loss, to help separate inflammation from functional problems
- People with Crohn’s disease or ulcerative colitis, to monitor activity, or to check if a flare is starting
- People with sudden or bloody diarrhoea, recent antibiotics, hospital stays or travel, who may have an infection
- People with unexplained iron-deficiency anaemia (low blood count from low iron) or a change in bowel habit, as part of an assessment
- Adults offered bowel cancer screening with a FIT kit, according to their local programme
Before the procedure
- Your clinic or lab will give you a container and instructions. Follow them exactly, because mistakes can spoil the result.
- For calprotectin, tell your doctor about anti-inflammatory painkillers (NSAIDs such as ibuprofen), aspirin and acid-reducing tablets (proton-pump inhibitors), which can raise the level. Do not stop any medicine unless told to.
- For a blood test in stool, your lab may ask you to avoid certain foods or medicines before some types of test, but a FIT usually needs no diet changes. Do not collect a sample during your period, when you have bleeding piles (haemorrhoids) or when urine is mixed in.
- For culture, collect the sample while the diarrhoea is active, ideally before taking antibiotics or anti-diarrhoea medicine unless your doctor advises otherwise.
- You do not need to fast or have sedation. Wash your hands well afterwards.
During the procedure
Pass the stool onto clean paper or a collection device placed over the toilet bowl, taking care that it does not touch the toilet water or mix with urine. Use the small spoon or stick in the container to scoop up the amount shown, and close the lid tightly. Label the container with your name and date, as instructed. Some kits ask for samples from different parts of the stool or on several days. Handle the sample with gloves or wash your hands carefully, and do not put in too much.
After the procedure
Deliver the sample to the lab or clinic as soon as possible, or as instructed; some samples must be kept cool or delivered within a few hours, and a FIT kit may be mailed or returned within a time limit. Nothing else is needed and you can go on with your day. If the result is abnormal, your doctor may advise further tests, usually a colonoscopy or other imaging.
Risks
- There is no physical risk; the test is not painful or invasive.
- The tests are not perfect. A high calprotectin can happen without IBD (for example with infection, NSAIDs or polyps), and a normal level makes inflammation unlikely but does not completely exclude it.
- A negative blood test in stool does not rule out a polyp or cancer, since bleeding can come and go. A positive result does not mean cancer, since haemorrhoids, ulcers and other causes can bleed too.
- Cultures can miss some germs, and some tests (such as PCR panels) can detect germs that are not the cause of symptoms. Results are read together with your story.
- Do not wait for a result if you have severe or bloody diarrhoea, high fever, severe belly pain, dehydration, or black stools; seek medical care straight away.
When you get results
Alternatives if you decline
Blood tests (such as CRP, a marker of inflammation) give some information but are less specific for the gut. A colonoscopy or sigmoidoscopy allows direct viewing and biopsies and is the standard way to confirm inflammation, polyps or cancer, but it needs preparation and is more invasive. Scans such as MR enterography can look at the small bowel. Stool tests are often used first because they are simple and non-invasive. Declining them may mean a camera test is done instead, or a problem is found later.
Questions to ask your doctor
Save this list or print it before your appointment — doctors appreciate prepared patients.
- Which stool test do I need, and what question does it answer?
- Should I stop any medicines, such as anti-inflammatory painkillers, before collecting the sample?
- How soon do I have to return the sample?
- If the result is abnormal, will I need a colonoscopy?
- How often should I repeat calprotectin if I have IBD?
Was this guide helpful?
Status: Approved for publication by SGA; individual clinician review is ongoing · Published 24/04/2026
For general education only; it does not replace your doctor’s advice. Individual clinician review of this guide is ongoing. SGA clinician? Review this guide