Quick answer: The results of a stool test indicate whether there is bleeding, inflammation, infection or a malabsorption disorder in the digestive system. Abnormal findings do not always indicate a serious condition, but they always require assessment by a gastroenterologist to ensure an accurate diagnosis.
You are handed a piece of paper full of numbers and Latin terms — and you have no idea what it means. This situation is familiar to almost every patient who sends a stool sample for laboratory analysis. The results of a stool test are a key diagnostic tool, enabling the doctor to gain an insight into the condition of the digestive system, even in the absence of obvious symptoms.
This article explains in detail the different types of stool tests available, what constitutes a normal and an abnormal result, when further investigation is required — and when it is advisable to consult a gastroenterologist.
What is a stool test, and why are the results important?
A stool test is a simple, painless diagnostic procedure: the patient collects a sample at home and sends it to a laboratory for analysis. By analysing the sample, the doctor can gain an insight into the functioning of the digestive system, the condition of the gut flora, and any infections, inflammatory processes or bleeding.
One of the greatest advantages of this test is that it can detect abnormalities that do not yet cause any symptoms. Based on the results of the stool test, the doctor can decide whether further investigation — such as a colonoscopy — is necessary, or whether close monitoring is sufficient.
What types of stool tests are there?
Not all stool tests measure the same things. Below you will find a description of the most commonly used types of tests and their clinical significance.
Detection of occult (hidden) blood – what does a positive result mean?
A faecal occult blood test (known as an FOBT or FIT test) checks for hidden blood in the stools that is not visible to the naked eye. There are two main types:
- iFOBT (immunohistochemical test): It directly detects human haemoglobin (a blood protein). It is particularly sensitive to lower gastrointestinal bleeding and does not require any prior dietary preparation.
- gFOBT (guaiac-based test): This is a highly sensitive method, although the results may be affected by the consumption of red meat or raw vegetables. It is therefore advisable to avoid these for at least 3 days before the test.
What does a positive result indicate? A positive stool test result does not automatically mean cancer. It may be caused by haemorrhoids, enteritis, a polyp or an ulcer. However, in the event of any positive finding, a colonoscopy is necessary to determine the exact cause. If the colonoscopy yields a negative result, a gastroscopy may also be warranted to rule out a source in the upper gastrointestinal tract.
Faecal calprotectin – what does an elevated level indicate?
Calprotectin is a protein produced by inflammatory white blood cells in the intestinal wall. Its level in the stool directly reflects the inflammatory state of the intestinal mucosa.
Normal values depend on age:
- Aged 2–10: A level below 165 µg/g is considered normal
- Aged 10–60: Below 50 µg/g is normal
- Aged 60 and over: 110 µg/g is the acceptable upper limit
A value above 250 µg/g indicates active inflammation and may signal a flare-up of the disease up to three months in advance. Calprotectin plays a crucial role in distinguishing between inflammatory bowel diseases (Crohn’s disease, ulcerative colitis) and irritable bowel syndrome (IBS) — in the latter, calprotectin levels remain normal.
It is important to note that in cases of microscopic colitis, calprotectin levels do not rise; therefore, this test alone is not sufficient for this condition.
M2-PK marker – when should colorectal cancer be suspected?
The M2-PK marker indicates changes in the metabolism of tumour cells. If its value exceeds 4.00 U/mL If there are any signs suggesting the presence of bowel cancer or polyps, a colonoscopy is absolutely essential.
Microbiological culture – detection of infections
Stool culture identifies pathogens: bacteria (e.g. Salmonella, Shigella, Campylobacter, Clostridium difficile), viruses and parasites (e.g. Giardia lamblia). It is recommended that this test be carried out, particularly in cases of diarrhoea or before starting immunosuppressive treatment.
Helicobacter pylori faecal antigen test
This study focuses on the active H. pylori detects infection in a stool sample. A positive stool test result indicates an active infection. Important: you must stop taking proton pump inhibitors and antibiotics 2–4 weeks before the test, as these can cause false-negative results.
Examination of steatorrhoea
If the stool contains more than 7 grams of fat per day, this indicates a malabsorption disorder. The results of this stool test may indicate pancreatic insufficiency, coeliac disease (gluten intolerance) or other digestive problems.
What do normal stool test results mean?
Normally, stools:
- Contains no detectable blood (occult blood negative)
- It is free from pathogens and parasites
- Shows a normal calprotectin level (depending on age)
- It does not contain an excessive amount of fat
It is important to note that a negative result does not completely rule out bowel diseases. If symptoms persist — such as persistent abdominal pain, anaemia or unintentional weight loss — your doctor may recommend a colonoscopy even if the results of the stool test appear normal.
Abnormal stool test results: when should you seek medical attention?
If the following symptoms occur — particularly if test results are positive — you should consult a gastroenterologist immediately:
- Blood in the stools (whether visible or hidden)
- Chronic or recurrent diarrhoea
- Unexplained weight loss
- Persistent abdominal pain or bloating
- Iron deficiency anaemia
- A sudden change in bowel habits
- Elevated calprotectin level
- Positive M2-PK marker
These are what are known as „alarm symptoms”, which require a detailed investigation.
What should you do if the results of a stool test are abnormal?
Abnormal test results are not, at this stage, a cause for panic, but they do clearly indicate that a specialist assessment is required. To reach a diagnosis, the gastroenterologist will decide on the next steps based on a comprehensive assessment of the test results, symptoms and medical history.
The most commonly performed tests in the event of a positive result:
- Colonoscopy: This is the first-line investigation recommended in the event of a positive occult blood test, elevated calprotectin or a high M2-PK level. It also allows for the immediate removal of polyps and the taking of tissue samples.
- Gastroscopy: If the colonoscopy yields a negative result, or if there is a suspicion of upper gastrointestinal tract disease (e.g. an ulcer, H. pylori infection, iron-deficiency anaemia).
- Combined examination: In cases of complex symptoms or concurrent involvement of the upper and lower digestive tracts, both examinations can be carried out during a single appointment.
Endomedix’s professional approach in the event of abnormal findings
Endomedix Diagnostic Centres is Hungary’s largest private gastroenterology network, currently providing care in more than ten towns and cities — including Budapest, Debrecen, Miskolc, Győr and Veszprém. Endomedix’s gastroenterologists have decades of experience in the diagnosis and treatment of digestive system disorders.
Endoscopic procedures carried out at Endomedix following abnormal stool test results For medical reasons, it is carried out exclusively under general anaesthesia, not under sedation. Intravenous propofol anaesthesia is always supervised by an experienced anaesthetist. General anaesthesia ensures that the patient undergoes the examination pain-free, whilst allowing the doctor to carry out the procedure precisely and without disruption.
In addition, Endomedix uses CO₂ insufflation during examinations, which means that, unlike with the traditional air-based method, there is no painful bloating or tightness following the procedure.
If the results of a stool test are abnormal, or if you have digestive problems, the first step is a face-to-face consultation with a specialist in gastroenterology, where the specialist will determine the necessary diagnostic steps.
If, based on the findings, a colonoscopy is required, the COLONOSCOPY UNDER ANAESTHESIA Available at any Endomedix centre, with a quick booking option.
Don’t put off getting checked out
The results of a stool test are not just a piece of paper — they provide a window into the state of the digestive system. Early detection can save lives: colorectal cancer, for example, is one of the most treatable forms of cancer if diagnosed in time.
If you have received abnormal test results or have been experiencing symptoms for some time, don’t wait any longer. Book an appointment at one of Endomedix’s centres, where our team of experts will provide you with a quick, accurate and pain-free examination.
Frequently Asked Questions (FAQ)
What does it mean if a stool test comes back positive for blood?
A positive result indicates hidden bleeding in the gastrointestinal tract. This may be caused by haemorrhoids, polyps, inflammatory bowel disease or — less commonly — a cancerous lesion. In the event of any positive result, a colonoscopy is required to determine the exact cause. A positive result is not a diagnosis in itself, but it does require further investigation by a gastroenterologist.
What is the normal calprotectin level in adults?
For people aged 10–60, a value below 50 µg/g is considered normal. For those over 60, the threshold is 110 µg/g. A value higher than this may indicate active bowel inflammation, and the gastroenterologist will decide on the necessary next steps — typically, a colonoscopy.
When should you change your diet before a stool test?
It is advisable to avoid red meat, raw vegetables and high doses of vitamin C for at least 3 days before a guaiac-based (gFOBT) faecal occult blood test, as these can distort the result. No such dietary restrictions are necessary for the immunohistochemical (iFOBT) test.
Is a colonoscopy necessary if the stool test result is negative?
Even if the result is negative, bowel disease cannot always be ruled out. If persistent symptoms — such as anaemia, abdominal pain or weight loss — are present, or if there is a high risk (e.g. over the age of 50, a positive family history), the doctor may recommend a colonoscopy even if the test result is negative.
What symptoms indicate the need for a stool test?
A stool test is recommended in cases of bloody or black stools, persistent diarrhoea, unexplained weight loss, chronic abdominal pain, bloating or iron-deficiency anaemia. These are known as ‘alarm symptoms’, which necessitate a detailed gastroenterological investigation.
What is the difference between IBS and inflammatory bowel disease, based on stool test results?
Irritable bowel syndrome (IBS) is a functional disorder — there is no actual inflammation in the body, so calprotectin levels remain normal. In inflammatory bowel diseases (Crohn’s disease, ulcerative colitis), by contrast, calprotectin levels are significantly elevated, and endoscopic examination also reveals visible lesions. A gastroenterological examination is required for accurate differentiation.
How do I book an appointment at Endomedix?
Endomedix Diagnostic Centres can be contacted on working days, Monday to Friday, between 09:00 and 17:00, by calling +36 1 413-2500 or online via the Endomedix website. The network has centres in more than ten towns and cities across the country, so the nearest centre is easy to reach.
