Tests for IBS
Standard tests
It is a good idea to ask your doctor/nurse for a printout of results for your records. You can print-off a check list sheet from the bottom of this page.
The following tests are the minimum that should be done for all types of IBS i.e. diarrhoea or constipation or "mixed" bowel habit (i.e.
both diarrhoea and constipation), with or without gas / bloating:
Blood tests
AND one of these:
What a calprotectin test result means
IN ADDITION to these general tests, you also need some other tests depending on your MAIN bowel SYMPTOM:
Diarrhoea (as "main" problem)
Constipation (as "main" problem)
Lower tummy / pelvic pain / "all the time" lower tummy bloating
Most of these tests are quite “general” and besides the coeliac screen (looking for an “allergy” to gluten that occurs in many grains), they do not specifically look at the gut. But, they do give a very good overview of whether there might be something other than IBS going on.
By the way, the coeliac blood test is only accurate if there has been enough gluten in your diet for the preceding 6 weeks (equivalent of
about a slice or two of normal bread each day). When it comes to diagnosing coeliac disease, the bottom line is: "No gluten, No test"!
The gene tests (for HLA DQ2 and DQ8- a blood test), which do not need gluten to be eaten, cannot tell you whether you have coeliac disease just whether you are: (a) extremely unlikely to have it (both DQ2 and DQ8 negative), or (b) there is a possibility but not a certainty (either DQ2 or DQ8 positive).
Do discuss tests with your doctor or nurse and highlight to them if you have any family history of bowel or ovarian cancer or indeed ANY particular concerns.
Again, the tests are there to make sure that nothing else is happening. Of course they will be normal / negative in the majority of people and that is a good thing and of course, good to know! But remember, IBS is more about "symptoms" rather than tests!
Why have tests - why not just apply logic?
Trying to rationalize things just does not work with the bowel for two reasons: (a) every tummy condition shares the same symptoms; (b) our tummies are not machines, if something goes wrong we can get a huge range of symptoms that vary from person to person.
“How could I have an allergy if I’m 30 years old now and have been eating wheat all my life…”
"It doesn’t feel like inflammation…”
"It definitely feels inflamed"
“I’ve had it for years…”
Trying to rationalize and link particular changes in bowel habit, or symptoms and where they are in the tummy to specific conditions, just doesn't work! Pretty well any condition that affects the tummy will "share" the same symptoms. Trawling the internet to come up with a diagnosis can become hugely confusing and frustrating very quickly because "everything" has the same symptoms. The reason that "specialists" earn their money is that they have been trained, as well as learning from experience, how to filter all the possible diagnoses- they put you and your symptoms in perspective.
Other tests
We know diet can be very helpful for IBS, so, there must be tests looking at our body's reaction to specific foods? Yes and no is the answer.
One area of confusion around tests is when people start to use the phrases food “allergy” and food “intolerance” as meaning the same thing. They are very, very, very different (!) even though they feel the same to us. They do after all share the same symptoms!
Importantly, there is no such thing as a test for gluten / wheat “intolerance” other than challenging ourselves by eating some and seeing how our gut feels afterwards. There is though a blood test for the gluten "allergy" called coeliac Disease. This is discussed in greater depth elsewhere.
Tolerance tests
These tests see if our guts are intolerant (i.e. can’t cope very well) to milk, fruit or some vegetables. The intolerance is specifically for the natural sugars that they contain: lactose (the sugar in milk / dairy) and fructose (the sugar in fruit / some vegetables).
These tests are really looking for "cause" (if I eat this) and "effect" (will I get symptoms?).
So, Tolerance tests are mainly used to guide diet- if the test is normal / negative, then those foods shouldn’t cause much trouble and that part of the diet can be left alone. Doing such tests is by no means essential; we can definitely find the right diet without them.
The commonest type of Tolerance test is the “Breath” test: you swallow a pure form of the particular sugar and then blow every 15 minutes
(over about two and a half hours) into a detector which picks up either the hydrogen gas (or less often measured, methane gas)- into which the normal lower-bowel gut bacteria transform these sugars.
There are other ways of checking for Lactose intolerance. There is the option to do a series of blood tests over a few hours after a challenge. There is also the possibility of checking for lactose intolerance by taking a small bowel biopsy at endoscopy (this checks for the amount of the enzyme Lactase that the body needs to cut up the lactose molecule). Both of these methods are obviously less "user friendly" than doing a Breath Test and no more accurate.
Tests for gut bacteria and candida etc.
Another Breath Test checks for a slightly vague, but important, condition called “Small Intestine Bacterial Overgrowth" (SIBO). We
talk about this in other sections.
What about other tests? Many laboratories offer stool samples to check for "high" levels of candida (a yeast that we all have normally in the bowel) or "odd" bacteria (such as Blastocystis hominis and others). There is no scientific measure of a "normal" amount of candidia and there is no good proof that any of these "bugs" have anything to do with IBS. So, the value of doing these tests is very questionable (we're being polite here!). That is why they are often not encouraged by doctors or covered by private health insurance.
It is difficult to know, similarly, how helpful are some quite expensive blood tests checking for food allergies (IgG Allergy testing).
Such IgG testing does come up with a "number" for the effect that a range of certain food extracts have on a blood sample in a laboratory, but, what does that mean in the real world and in our guts? Nobody really knows! Desperately seeking "definite" answers that nobody can really give, can become an unnecessary and unjustifiably expensive business!
Imaging tests
Scans like CT of Abdomen / Pelvis, MRI of Small Bowel or doing a Capsule Video Endoscopy ("Pill" camera) have no general role in investigating or diagnosing IBS. They may be done by your doctor though if a symptom "does not feel quite right" or if our IBS symptoms do not respond to treatment as would be expected. CT scans involve radiation, so are best avoided, in favour of MRI if possible.
Tests to avoid
Don't let your suffering drive you to have any test that someone suggests just because "doing something is better than nothing". They can cost you a lot of money and emotional investment. Specialist medical organizations* strongly suggest that there is no value in having the following tests:
It is a good idea to ask your doctor/nurse for a printout of results for your records. You can print-off a check list sheet from the bottom of this page.
The following tests are the minimum that should be done for all types of IBS i.e. diarrhoea or constipation or "mixed" bowel habit (i.e.
both diarrhoea and constipation), with or without gas / bloating:
Blood tests
- Full Blood Count (Complete Blood Count is another name), urea, creatinine and electrolytes
- Coeliac screen
- ESR ("Sed rate") and/or CRP (C-Reactive protein)
AND one of these:
- Endoscopy (a "tube" camera that looks inside our body): the two commonest endoscopy procedures are a Flexible Sigmoidoscopy which is a more limited test (looks at half the colon [the lower bowel]) than a Colonoscopy which inspects all the way around the colon.
- Faecal calprotectin: a simple stool sample test that is being used more and more as a "non-invasive" substitute for "tube" tests. It checks
for lower bowel inflammation and other conditions. (Over the age of 40 years or so, probably better to have an endoscopy test).
What a calprotectin test result means
- A "normal" calprotectin result is very re-assuring for there being nothing else in the lower bowel.
- If the calprotectin test comes back as very high, it is best to have a "tube" test.
- If the result is a little "high", then it is often repeated. If that comes back as normal, that is OK. But, should it come back as "high"
again, a tube test is needed.
IN ADDITION to these general tests, you also need some other tests depending on your MAIN bowel SYMPTOM:
Diarrhoea (as "main" problem)
- Stool sample for "culture and sensitivity" that checks for infection (and, if you have been somewhere exotic another stool sample for "ova
and parasites" that checks for worms etc.)
Constipation (as "main" problem)
- Calcium level (a blood test)
- Thyroid function tests (a blood test). The thyroid is a gland in our necks that controls the body's metabolism; when under-active it can cause constipation.
Lower tummy / pelvic pain / "all the time" lower tummy bloating
- CA125 (a blood test). This checks for ovarian cancer.
- Ultrasound of pelvis.
Most of these tests are quite “general” and besides the coeliac screen (looking for an “allergy” to gluten that occurs in many grains), they do not specifically look at the gut. But, they do give a very good overview of whether there might be something other than IBS going on.
By the way, the coeliac blood test is only accurate if there has been enough gluten in your diet for the preceding 6 weeks (equivalent of
about a slice or two of normal bread each day). When it comes to diagnosing coeliac disease, the bottom line is: "No gluten, No test"!
The gene tests (for HLA DQ2 and DQ8- a blood test), which do not need gluten to be eaten, cannot tell you whether you have coeliac disease just whether you are: (a) extremely unlikely to have it (both DQ2 and DQ8 negative), or (b) there is a possibility but not a certainty (either DQ2 or DQ8 positive).
Do discuss tests with your doctor or nurse and highlight to them if you have any family history of bowel or ovarian cancer or indeed ANY particular concerns.
Again, the tests are there to make sure that nothing else is happening. Of course they will be normal / negative in the majority of people and that is a good thing and of course, good to know! But remember, IBS is more about "symptoms" rather than tests!
Why have tests - why not just apply logic?
Trying to rationalize things just does not work with the bowel for two reasons: (a) every tummy condition shares the same symptoms; (b) our tummies are not machines, if something goes wrong we can get a huge range of symptoms that vary from person to person.
“How could I have an allergy if I’m 30 years old now and have been eating wheat all my life…”
"It doesn’t feel like inflammation…”
"It definitely feels inflamed"
“I’ve had it for years…”
Trying to rationalize and link particular changes in bowel habit, or symptoms and where they are in the tummy to specific conditions, just doesn't work! Pretty well any condition that affects the tummy will "share" the same symptoms. Trawling the internet to come up with a diagnosis can become hugely confusing and frustrating very quickly because "everything" has the same symptoms. The reason that "specialists" earn their money is that they have been trained, as well as learning from experience, how to filter all the possible diagnoses- they put you and your symptoms in perspective.
Other tests
We know diet can be very helpful for IBS, so, there must be tests looking at our body's reaction to specific foods? Yes and no is the answer.
One area of confusion around tests is when people start to use the phrases food “allergy” and food “intolerance” as meaning the same thing. They are very, very, very different (!) even though they feel the same to us. They do after all share the same symptoms!
Importantly, there is no such thing as a test for gluten / wheat “intolerance” other than challenging ourselves by eating some and seeing how our gut feels afterwards. There is though a blood test for the gluten "allergy" called coeliac Disease. This is discussed in greater depth elsewhere.
Tolerance tests
These tests see if our guts are intolerant (i.e. can’t cope very well) to milk, fruit or some vegetables. The intolerance is specifically for the natural sugars that they contain: lactose (the sugar in milk / dairy) and fructose (the sugar in fruit / some vegetables).
These tests are really looking for "cause" (if I eat this) and "effect" (will I get symptoms?).
So, Tolerance tests are mainly used to guide diet- if the test is normal / negative, then those foods shouldn’t cause much trouble and that part of the diet can be left alone. Doing such tests is by no means essential; we can definitely find the right diet without them.
The commonest type of Tolerance test is the “Breath” test: you swallow a pure form of the particular sugar and then blow every 15 minutes
(over about two and a half hours) into a detector which picks up either the hydrogen gas (or less often measured, methane gas)- into which the normal lower-bowel gut bacteria transform these sugars.
There are other ways of checking for Lactose intolerance. There is the option to do a series of blood tests over a few hours after a challenge. There is also the possibility of checking for lactose intolerance by taking a small bowel biopsy at endoscopy (this checks for the amount of the enzyme Lactase that the body needs to cut up the lactose molecule). Both of these methods are obviously less "user friendly" than doing a Breath Test and no more accurate.
Tests for gut bacteria and candida etc.
Another Breath Test checks for a slightly vague, but important, condition called “Small Intestine Bacterial Overgrowth" (SIBO). We
talk about this in other sections.
What about other tests? Many laboratories offer stool samples to check for "high" levels of candida (a yeast that we all have normally in the bowel) or "odd" bacteria (such as Blastocystis hominis and others). There is no scientific measure of a "normal" amount of candidia and there is no good proof that any of these "bugs" have anything to do with IBS. So, the value of doing these tests is very questionable (we're being polite here!). That is why they are often not encouraged by doctors or covered by private health insurance.
It is difficult to know, similarly, how helpful are some quite expensive blood tests checking for food allergies (IgG Allergy testing).
Such IgG testing does come up with a "number" for the effect that a range of certain food extracts have on a blood sample in a laboratory, but, what does that mean in the real world and in our guts? Nobody really knows! Desperately seeking "definite" answers that nobody can really give, can become an unnecessary and unjustifiably expensive business!
Imaging tests
Scans like CT of Abdomen / Pelvis, MRI of Small Bowel or doing a Capsule Video Endoscopy ("Pill" camera) have no general role in investigating or diagnosing IBS. They may be done by your doctor though if a symptom "does not feel quite right" or if our IBS symptoms do not respond to treatment as would be expected. CT scans involve radiation, so are best avoided, in favour of MRI if possible.
Tests to avoid
Don't let your suffering drive you to have any test that someone suggests just because "doing something is better than nothing". They can cost you a lot of money and emotional investment. Specialist medical organizations* strongly suggest that there is no value in having the following tests:
- Basophil histamine release/activation
- Lymphocyte stimulation
- Intra-dermal food injection
- Facial thermography
- Gastric juice analysis
- Endoscopic allergen provocation
- Hair analysis
- Applied kinesiology
- Provocation neutralization
- Allergen-specific IgG4
- Cytotoxicity assays
- Electrodermal test (Vega)
- Mediator release assay (LEAP)