Now you may have already known from my previous posts here in the
Much Ado about Poo Blog,
and on the
Kids Gastro Care Facebook page
that Coeliac disease is fairly common and thought to affect 1 in 100 people. The mainstay of treatment remains total and life-long exclusion of gluten from the diet.
When and how does Coeliac disease present ?
Coeliac disease can affect anyone of any age provided that gluten has already been introduced into the diet. However, despite it being so common, it is still under diagnosed, possibly because of the many different ways it can show manifest.
From being asymptomatic (no symptoms to speak of) to a variety of gastro-related symptoms including
- tummy ache
- change in bowel habits (constipation or more often loose stools)
- abdominal bloating
- loss of appetite
- vomiting
- weight loss
- A negative effect on growth, children may not be growing as tall as expected for parental heights
- or they may not pass through the stages of puberty as expected.
It can also affect other bodily systems including - the skin with dermatitis herpetiformis
- the bones with relatively easily sustained fractures
- the blood system with difficult to treat anaemia.
- The liver may show changes (on liver related blood tests)
- very rarely the brain can be involved
- In women of childbearing age it can also be a cause of fertility related issues.
How does a paediatric gastroenterologist diagnose coeliac disease
The way coeliac disease is diagnosed in adults involves a combination of clinical history and examination, blood tests and endoscopy with biopsy samples from the small bowel. It is imperative to remain on gluten throughout the diagnostic process until it is complete as otherwise these tests are not accurate and there can be diagnostic confusion. See the brilliant
Coeliac UK website
for more details about this
here.
Until recently coeliac disease was diagnosed in a very similar fashion in children as well, that is to say a combination of symptoms, positive
blood tests and gut biopsies
obtained during an upper GI endoscopy.
In children it is important to remember that all endoscopy should ideally be carried out by paediatric gastroenterologists and the procedure is performed under general anaesthetic rather than the sedation used in adults. This has become the accepted standard of care for paediatric endoscopy and is how I do things at
Kids Gastro Care.
For more about children's endoscopy please have a look at the
useful resources page on the Kids Gastro Care (KGC) website where you can find a child friendly video discussing this.
Blood tests
The blood tests involved measure an IgA antibody to an enzyme called Tissue Transglutaminase or tTG-IgA test for short. Alongside this test one should also always test for a blood protein called Immunoglobulin A (IgA) as deficiency in this protein can lead to so called false negative results when measuring tTG. Other blood tests are also used to confirm a diagnosis including endomyseal antibody (EMA) and in the last few years a genetic marker test that looks at specific markers known as Human leucocyte antigens or HLA DQ2 and DQ8 has also been used.
Now the TTG blood test is a highly specific and sensitive test, so that when negative it is pretty good at ruling out coeliac disease. If there is also IgA deficiency as well, the test is much harder to interpret accurately. When positive it is a pretty good indicator that something is up in the small bowel, the most likely cause being coeliac disease.
The gut biopsies
The biopsies are small samples of tissue taken from the innermost layer or lining (mucosa) of the small intestine. The first part of the small intestine or duodenum is where most biopsies are taken from.
Now if I can take you back to Biology lessons of distant memory, the small intestine is the major site of absorbtion of nutrients in the body. Damage to this highly specialised absorbtive area leads to loss of the villi or finger like projections where absorbtion takes place and throws the body into a state of malabsorbtion and development of symptoms of pain, diarrhoea, weight loss etc.
To reach the small bowel to obtain these biopsies, an upper GI endoscopy or camera test is necessary
How was coeliac disease diagnosed in children before the tTG blood test was available...
Pre-dating the development of the blood test that measures the levels of antibody to Tissue transglutaminase (tTG) in those children in whom coeliac disease was suspected biopsies were essential. So going back to the 1970s, children would undergo a series of 3 endoscopic procedures with accompanying gut biopsies.
- the first would be to demonstrate the damage and changes in the small bowel associated with coeliac disease whilst on a normal (gluten containing diet),
- the second to show the recovery of the small intestinal mucosa or lining once placed on a gluten free diet for period of time
- and then the third to show the damage sustained when the child was challenged again with gluten to 'prove' the offending trigger was gluten. OUCH! or OUCH X 3!!!
So whats new Doc?
Since the introduction of the TTG blood test, the process for the diagnosis of coeliac disease changed dramatically.
If a child was suspected of having coeliac disease because of symptoms, a family history, or other blood test findings such as persistent iron deficiency anaemia, they would have a blood test to screen for it. The test would measure tTG and if they had a positive result they would then always go on to have an upper GI endoscopy and a set of biopsies whilst on a gluten containing diet, to show the damage sustained by the small bowel to confirm the diagnosis.
2012... a move away from blood tests and biopsy for all
In children, until 2012 the same methods as described above, were used to diagnose coeliac disease in all children. That is to say in all children, blood tests and biopsies
from the small bowel collected during upper GI endoscopy were needed. For more information about these procedures see the
Useful resources page on the Kids Gastro Care website here
In 2012, this all changed. Given that the tTG test is such a good test for coeliac disease, in select cases it was deemed possible to diagnose the condition without need to resort to endoscopy and biopsy. The higher the result of the tTG test, the greater the certainty of coeliac disease changes to be found at upper GI endoscopy.
The no-biopsy approach from 2012 for some not all
The criteria to fall into this group of patients included a child with symptoms consistent with coeliac disease alongside a strongly positive tTG result, more precisely if it was more than ten times the upper limit of normal for the laboratory in which it was being measured. So in the Lab at the Royal Free Hospital London where I have
my clinics and endoscopy lists, if it was more than 60, in combination with compatible symptoms and as well as the 2 other blood tests mentioned earlier (EMA and HLA tests) being positive, then that combination would be enough to diagnose coeliac disease.
This approach, a non-biopsy approach, was suggested only in this specific subset of paediatric patients fulfilling these criteria and also if the family are happy to go along with it. In all other cases, for example, no convincing symptoms, an associated condition such as Type 1 diabetes and a high tTG, a weakly positive tTG result, or at family request, then all those children would still need a biopsy.
In adult gastroenterology, this no biopsy approach has not been adopted (yet ?? ) and is a controversial area.
Fast forward to 2019..more changes ahead
And now we are entering another new era in the diagnostic pathway for coeliac disease in children. This latest guideline from ESPGHAN, is now advocating a
Biopsy avoidance approach in a much wider group of children.
The inclusion criteria has expanded greatly. So from now on, this would apply not only for children with obvious symptoms and strongly positive tTG blood test results but even in those with no symptoms at all and a strongly positive tTG result. The guidelines also remove the need for testing for HLA DQ2 or HLA DQ 8 markers.
So to summarise these latest developments:
if a child is suspected of having coeliac disease for whatever reason (symptoms or no symptoms etc) then they may be able to avoid having an upper GI endoscopy and small bowel biopsies if they have a combination of a strongly positive blood test result for tTG along with a positive EMA result on a second blood test sample.
Pitfalls in diagnosis of coeliac disease
I can not emphasise these points enough as from my experience of hundreds of cases they are still not always considered when referrals are made.
1) Prematurely removing or significantly reducing gluten intake before a confirmed diagnosis
When gluten is removed from the diet prematurely before the diagnostic process is complete it can often lead to confusion around a diagnosis. The child is then subjected to a gluten challenge or reintroduction of gluten in order to complete the diagnostic process more accurately.
It is essential that there has been enough gluten in the diet and for a sufficient length of time prior to testing
so that the blood tests can be reliably interpreted. If in doubt a paediatric dietician can help review your child's diet to ascertain if sufficient gluten has been ingested.
2) Forgetting to measure Total IgA at time of other tests
Other causes of confusion include having IgA deficiency. This is a fairly common from of immune system deficiency especially in the Caucasian population. Approximately 1 in 600 people generally are affected and it is even more common in those with coeliac disease.
See the information leaflet from the
primary immunodeficiency UK charity here
for more information about selective IgA deficiency.
In such a situation the standard tTG test becomes unreliable as it depends on there being enough IgA around.
What does a paediatric gastroenterologist do ? Specialist involvement in diagnosing coeliac disease
Being a specialist in the field I'm aware of these latest guideline developments at an early stage.
As with previous changes to disease specific and specialty guidelines, awareness of this new route to diagnosis will gradually increase over time among family doctors and my colleagues in general paediatrics. The guidelines suggest that diagnosis is made by a paediatric gastroenterologist. All of these points will be covered during a consultation with a
specialist in paediatric gastroenterology,
and as with all my consultations, shared decision making conversations are held with you and your child to work out the best next steps around managing the situation.
Should you find yourself in a scenario where coeliac disease is being suspected please make your doctor aware of these new guidelines and also ask for a referral to a
paediatric gastroenterologist.