Coeliac Disease Diagnosis and Tests

Coeliac disease diagnosis and tests. Coeliac disease (CD) (or gluten sensitive enteropathy) can present with many symptoms. If you have digestive and gut problems, a doctor may consider the diagnosis of coeliac disease, but if these are absent, and you have other general and mixed symptoms – which could easily indicate any number of health issues – it may not initially be suspected.

Some doctors retain the outdated idea that coeliac disease is a wasting disease, and will not consider it a possibility if patients are, for example, overweight – even though many patients are at diagnosis.

Testing  for coeliac disease – yes or no?

There are many conditions and situations that may justify testing for coeliac disease, and most are now specified in guidelines issued in 2009 by the National Institute for Health and Clinical Excellence (NICE).

Abnormal blood test results

Often, routine blood tests for other medical investigations alert doctors to a need for further tests, including those for coeliac disease. Irregular blood cells, low iron or calcium levels, or abnormal liver and kidney function markers, for instance, could indicate a problem.

In the absence of any coeliac disease symptoms, this is how many cases first reveal themselves, but as there are other reasons for these results, it does depend on your medical practitioner pursuing coeliac disease as a possibility along with other suspicions.

Common coeliac symptoms

Aside from the well-known digestive symptoms of diarrhoea, nausea, abdominal pain and so on, other symptoms that should be followed up with testing include faltering growth or failure to thrive (in children), sudden or unexplained weight loss, the unexplained presence of anaemia, and on-going tiredness or fatigue.

Less common coeliac symptoms

Testing should be considered in cases of dental enamel defects, depression or bipolar disorder, epilepsy, certain problems with the bones, unexplained fertility issues and unexplained hair loss.

Irritable bowel syndrome

Irritable bowel syndrome (IBS) is a gut disorder characterized by symptoms such as diarrhoea, constipation, alternating diarrhoea and constipation, bloating, abdominal pain, urgency, incomplete bowel movements and other related complaints.

It is a functional gut disorder – a problem with how the intestine works – rather than a structural one, in which there would be a physical abnormality detectable by scans, biopsies or examinations.

However, owing to the overlap of symptoms with coeliac disease, misdiagnoses of IBS are often made. Recently updated NICE guidelines for the diagnosis of IBS state that tests for coeliac disease must now be carried out and coeliac disease ruled out before an IBS diagnosis is made with confidence, but if your diagnosis was made some years ago, this may not have been undertaken. It is worth talking to your doctor about this, especially if you have been self-managing your IBS for some years. Research suggests that coeliac disease is four times as common in those who have received an IBS diagnosis than in the rest of the population, and hence all IBS patients should have coeliac disease tests.

Autoimmune conditions

You should be tested for coeliac disease if you have autoimmune thyroid disease or type 1 diabetes mellitus.

NICE guidelines state that doctors should ‘consider offering’ blood tests to those with one or more of several other autoimmune conditions, including Addison’s disease, autoimmune liver disease, and Sjögren’s syndrome. The incidence of coeliac disease among patients with these conditions varies, but averages about 5 per cent. It is usually preferable to test, especially if you have more than one autoimmune condition.

Family history

A first-degree relative – child, sibling, and parent – with coeliac disease means that you too should be tested.

Chromosomal syndromes

Coeliac disease is five to ten times more common in those with Williams’ syndrome, Turner’s syndrome or Down’s syndrome, and testing should be considered in these cases.

Before testing

Your doctor should explain several points before you or your child is tested for coeliac disease:

  • You should not stop consuming gluten or feeding it to your child – or reduce intake.
  • The blood tests that you or your child undergo cannot diagnose coeliac disease on their own.
  • Positive blood test results will mean that you or your child will probably need an endoscopy and biopsy.
  • Negative blood test results will mean that coeliac disease is unlikely, but may not rule out it arising in future.

The necessity of diagnosis

Possibly most important factor to understand before you undergo testing is why the end-result – a positive or negative diagnosis – is vital.

A confident positive diagnosis is needed to:

  • Avoid developmental or growth problems that can result with delays in diagnosing or failure to diagnose coeliac disease in children;
  • Ensure that children can subsequently receive care, treatment and monitoring of their development;
  • Ensure that you receive on going care from your doctor and gastroenterologist (specialist gut doctor);
  • Avoid the increased risks of longer-term complications of undiagnosed coeliac disease – which include osteoporosis, decreased fertility, under nutrition and a small increased risk of intestinal cancers;
  • Confirm that a gluten-free diet (GFD) – a tough undertaking – is indeed necessary;
  • Qualify you for gluten-free (GF) foods on prescription; Ensure that you receive help and advice from a dietitian on the gluten free lifestyle; and
  • Help to alert your first-degree relatives that they have an increased likelihood of coeliac disease and should also get tested.

A confident negative diagnosis is needed to:

  • Help to take your medical advisers a step closer to finding the root of any health problems you’re experiencing;
  • Ensure that there is no reason to restrict your diet unnecessarily; and
  • Help in part to confirm a diagnosis of IBS – which has its own treatments.

Gluten consumption

Undoubtedly the toughest challenge for many is having to continue to eat gluten – or feed it to their child – prior to testing. Blood testing detects antibodies to gluten, which are produced by the immune system of coeliacs. If you stop eating gluten, the body stops producing the antibodies, and the blood tests won’t reflect a true picture. It may be particularly hard to consume bread and pasta knowing that they could be harming you.

The recommendation from NICE and the charity Coeliac UK is to eat ‘some gluten in more than one meal every day for at least six weeks before testing’. At least 10 grams of gluten a day is thought to be needed – this can be made up of any combination of, for instance, slices of white bread (2–3 grams of gluten each), or whole wheat bread (4–5 grams each), digestive biscuits or rusks (1 gram each), a small serving of pasta (6 grams), and a Weetabix or Shredded Wheat (2 grams each).

Psychologically, it’s important to remind yourself how vital it is for you to do this to achieve the ultimate goal of an accurate result, and potentially a life of health and free of symptoms for you or your child. Try to comfort yourself with the knowledge that it will soon be over and you will have an answer. If you find it difficult, speak to your doctor. In some cases, it may be possible to give your child gluten powder hidden in foods that he or she does not associate with feeling poorly.

Blood tests 

Routine blood tests, for instance, to check for anaemia or liver function, can assist a diagnosis and serve to highlight specific health issues, but coeliac disease tests are key in the diagnostic procedure. These are very good, but not 100 per cent accurate, which means they cannot usually diagnose the disease alone.

The tissue transglutaminase test

The tissue transglutaminase (tTG or tTGA) test looks for antibodies to an enzyme – tissue transglutaminase – produced when the coeliac-affected gut tries to repair itself. It is the first-choice test for adults and children and is easy to perform. When coeliac disease is present in adults, it correctly confirms a positive diagnosis in at least 90 per cent of cases. When coeliac disease is absent, it correctly confirms a negative diagnosis at least 95 per cent of the time. The test may be less accurate in children.

The anti-endomysial antibody test

The anti-endomysial (EMA) test looks for antibodies against tissue called endomysium, which joins cells together. It is usually used as an additional test when the results of the tTG test are borderline or uncertain, although it is more expensive and difficult for medical teams to perform. When coeliac disease is present, it correctly confirms a positive diagnosis in 95 per cent of cases. When coeliac disease is absent, it correctly confirms a negative diagnosis 99 per cent of the time.

Total immunoglobulin A level

Both the tTG and EMA tests test for classes of antibodies called immunoglobulin A (IgA). Around 2 per cent of coeliac patients have IgA deficiency – natural low levels of this antibody. If the tTG and EMA tests are negative, an IgA deficiency test may be undertaken. If positive, alternative antibodies called immunoglobulin G (IgG) can be used to conduct the tTG and EMA tests instead.

HLA typing

Virtually all people with coeliac disease have one of two genetic tissue types – HLA-DQ2 or HLA-DQ8. Testing for these types, then, can also assist a diagnosis – but only in ruling out coeliac disease in their absence.

Home blood tests

Personal testing kits are now available. The Biotech Biocard™ Celiac Test, for instance, available from pharmacies, is a kit allowing you to take a small sample of your own blood and test it for coeliac IgA antibodies. The results are said to be as accurate as laboratory results, but of course false positives or false negatives are possible. In practice, there is always the danger that a false negative could offer false reassurance. A doctor is likely to insist on repeating a positive test.

Blood test results

If all blood test results are negative, and there is no other clinical reason to suspect coeliac disease, a confident negative diagnosis can be made. If all the blood test results are negative, but there remains a strong continuing clinical suspicion of coeliac disease – typical symptoms, perhaps teamed with strong family history or other autoimmune illnesses – then a referral for a biopsy of the gut lining may be given. If any of the key tTG or EMA blood test results are positive, you or your child will probably be referred to a gastroenterologist or paediatric gastroenterologist for a biopsy. However, because it is being increasingly realized that positive antibodies to coeliac disease can sometimes be temporary in children, there may be occasional circumstances when it is better to take no action and review the situation in six months or a year.

Endoscopy and biopsy

An endoscopy is an internal medical examination using an apparatus called an endoscope, which is passed into the body.

A biopsy is the removal of a little tissue from the body for examination.

An endoscopy and biopsy of the lining of the small intestine to check for coeliac-related damage is usually considered necessary in diagnosing coeliac disease. You or your child will have to attend the hospital out-patients department for the procedure, although young children will need to be admitted and given a general anaesthetic. Food and drink must be avoided for a period beforehand, but check with the endoscopy unit in advance. There may be a need to restrict some medications too. Intravenous sedation is available for those nervous of the procedure. Alternatively, a milder anaesthetic can be sprayed at the back of the throat.

A device is placed into your mouth to keep it open. Air will be passed into your body to expand it and allow the endoscopist to see better. The endoscope, which is a long flexible tube, is passed into the mouth, down the throat into the stomach, and then into the duodenum. The end of the endoscope has a light and a camera, and tiny forceps for obtaining small samples of the lining of the gut. Several samples will be taken from different areas, because the damage caused by coeliac disease can be patchy.

Typically the procedure will be over in half an hour. It is entirely painless, though if you have anaesthetic spray it will be slightly uncomfortable. The advantage of the spray over sedation is that you can leave the hospital soon after the procedure. If you are sedated, you will need to wait for several hours, be discharged into the care of a friend or relative, and rest afterwards. You should be back to normal within 24 hours, though you will have a slight sore throat.

The tissue samples are sent to a laboratory for microscopic analysis.

In the case of suspected dermatitis herpetiformis, a small biopsy of unaffected skin is taken.

Is a biopsy necessary?

For some years, the biopsy has been considered the ‘gold standard’ means of confirming a diagnosis, but improvements in blood testing and in how well coeliac disease is recognized among specialists now mean that this view is being increasingly challenged, with some gastroenterologists believing that it may sometimes be better not to put a patient through the procedure.

A study from Derby in 2008 found that tTG test results above a certain level could be 100 per cent accurate in diagnosing coeliac disease, and that around 50 per cent of tested cases reached this level – meaning that half of patients could avoid a biopsy and be confidently diagnosed on the strength of the blood test alone. Accordingly, some gastroenterologists have begun to adopt this policy when clinical suspicion is strong and tTG readings are high. Diagnosing without a biopsy is also cheaper and does not add a burden to health service resources.

A possible advantage of this from a wider perspective is that it could encourage more people to come forward. Some patients with symptoms may be reluctant to present to their doctor and pursue a diagnosis because of fear of a biopsy.

But there are advantages for retaining biopsy as a means of diagnosis. It offers certainty – and some feel nobody should have to go on a gluten free diet if there is any possible doubt.

Some also consider it vital to measure the scale of characteristic gut lining erosion as a ‘benchmark’. Should the patient continue to experience symptoms after, say, six months on a gluten free diet, a biopsy may sometimes become essential. Without an earlier one for comparison, it would be impossible to learn how much healing has taken place in the meantime.

The results of a biopsy can also serve as a powerful motivator to stick rigidly to a gluten free diet: without one, a patient may be less likely to appreciate the seriousness of his or her condition and the internal damage that comes with it, and be more tempted to stray occasionally.

This issue is subject to much debate among the coeliac community, and the recommendations are likely to be modified over time, perhaps because of further improvements in blood testing.

Remember that nobody can force you or your child to have an endoscopy and biopsy, and that each case is unique. Discuss options with your medical team.

Video capsule endoscopy

Video capsule endoscopy involves swallowing a pill that has been fitted internally with a tiny camera that takes images as it moves through the patient’s intestine. The photographs are transmitted to a receiver worn on a belt by the patient, and these can be downloaded by doctors to look for inflammation or erosion of the gut’s lining.

It is not yet approved as a diagnostic technique for coeliac disease, and studies on its effectiveness for this purpose have found mixed results, albeit some quite positive. That said, it is becoming increasingly available through the health service.

Diagnosis of coeliac disease

Following testing, there are several possible results.

Blood positive and biopsy positive

This combination of results confirms coeliac disease.

Blood positive and biopsy negative

This combination of results could indicate absence of coeliac disease and false-positive blood test results. A negative HLA typing test can strengthen the negative diagnosis. This could also be potential coeliac disease, however, which can develop into typical or atypical coeliac disease over time. It is likely that your doctor will advise you or your child to stick to a normal, gluten-containing diet, and keep the situation under regular review, with perhaps repeat testing in future.

Blood negative and biopsy positive

There are other possible causes of inflammation to the lining – recent gastroenteritis, other gut disorders – and these may need to be excluded. This is especially true of babies and infants, who may have other food intolerances that cause the damage. Generally, though, this result will be viewed as coeliac disease, and treated as such.

Blood negative and biopsy negative

Coeliac disease is currently absent. However, there may be justification to keep monitoring the situation and repeat the blood tests in the future – for instance, in cases of a strong family history or in patients with other autoimmune conditions.

Blood positive and biopsy not performed

If tTG levels are high, and other results suggest coeliac disease, this may be enough for some gastroenterologists to diagnose the disease. It is in infants and babies that there is greater debate regarding performing a biopsy. Some parents may refuse to allow it on their sick children. A cautious positive diagnosis may still be made in these cases, if other criteria are met, such as positive HLA typing and the presence of obvious symptoms (failure to thrive). In this case, a gluten free diet will be recommended, and a diagnosis reinforced if there is health improvement and subsequent negative blood tests. 

Testing negative

A negative test may leave you feeling relieved that you don’t have coeliac disease but frustrated that you haven’t found the cause of any symptoms. Rest assured that you are a step closer, having ruled out one of the possibilities. IBS aside, other conditions may need to be considered.

Non-coeliac gluten intolerance

The concept of non-coeliac gluten intolerance remains controversial but is increasingly being accepted by some specialists, as some people in whom coeliac disease has been ruled out seem to experience unpleasant symptoms on a regular diet for which relief is obtained on a gluten free diet. It is possible that some may be experiencing nothing more than the health benefits derived from the more nutritionally diverse diet that a gluten free diet may compel patients to follow – rich as it is likely to be in alternative whole grains, fruit, vegetables, nuts, seeds and unprocessed foods – but others may indeed be reacting to gluten in a way not presently understood. This can only be diagnosed through an exclusion diet under the guidance of a dietitian.

Other food sensitivities

Lactose intolerance is the inability to digest lactose (milk sugar), caused by a deficiency in lactase, a digestive enzyme. Its symptoms are frothy diarrhoea, abdominal ‘gurgling’, and bloating. Reliable testing (via a breath test) is available, but most other intolerances can only be tested for using an exclusion diet. Children, especially, may be more prone to cow’s milk protein intolerance or soya intolerance.

Inflammatory bowel diseases

Inflammatory bowel diseases, such as Crohn’s disease or ulcerative colitis, may need to be considered.

Chronic fatigue syndrome or myalgic encephalomyelitis

Chronic fatigue syndrome or myalgic encephalomyelitis (ME) is an illness characterized by extreme tiredness, muscle fatigue, problems with concentration and depression, and general ill health. Symptoms may include digestive problems similar to those found in IBS and coeliac disease.

Invalid testing techniques

There are a number of privately available tests and alternative testing techniques for food sensitivities for which bold claims of their diagnostic abilities are sometimes made by their manufacturers and practitioners. None can diagnose coeliac disease, and in fairness the manufacturers may well make this clear. However, reference may be made to ‘gluten intolerance’, ‘gluten allergy’ or ‘wheat sensitivity’, among other food intolerances. The tests include:

  • Electro dermal or Vega testing (available at some high-street health stores);
  • Leukocytotoxicity testing (e.g. NuTron, antigen leukocyte cellular antibody test – ALCAT);
  • IgG testing (e.g. YorkTest’s FoodScan, CNS’s Food Detective).

There is no evidence to support the use of the first two, which are regarded as unscientific. There is very little evidence behind the third, and most experts in the field believe it to be of no diagnostic use either.

It is suspected that customers who report improvements after acting on the results and recommendations of such tests are often benefiting from a more nutritious diet. Wheat and dairy are typically identified as problematic foods, and this constrains consumers to cut out all the calorific or junk food in which these two foods happen to be found – pies, pizzas, hot dogs, burgers, doughnuts, cakes, biscuits and so on. These inevitably have to be replaced by more healthy whole grains, vegetables, fruits, dried fruit and nuts. Often, it is the inclusion of these wholesome foods – not the exclusion of theoretically problematic ones – that is the main reason for improved health.

Some complementary practitioners of applied kinesiology, the Nambudripad allergy elimination technique (NAET), homoeopathy and many other techniques may also make claims to be able to diagnose (and possibly treat) food sensitivities. These practices have no place in modern medicine, and have either failed scientific scrutiny or been discredited by researchers. All should be avoided when seeking a diagnosis or treatment of coeliac disease of any kind.

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