This is a post I wrote during Coeliac Week this year – useful rundown of testing issues.
The biggest problem is that many coeliacs are going undiagnosed. Many people will be posting about the symptoms to look for (although weight loss, diarrhoea, failure to thrive are certainly not the only ones to look out for – I will come back to this in a later post maybe), so I will post about testing to give you something different:
Q: What is the best way to confirm coeliac disease?
A: The supposed ‘gold standard’ of diagnosis is a biopsy of the small intestine. However, if a biopsy comes back negative, it doesn’t mean you are not coeliac. That sounds like heresy no doubt to coeliac ‘experts’ but bear with me.
Some researchers have found that coeliac disease can exist without villi atrophy. As recently as 2010, Kurppa Kalle published a paper called ‘Celiac Disease Beyond Villous Atrophy‘ where they found children who tested positive for markers of tissue damage, in this case EMA, had no villi damage but did well on a gluten free diet. They concluded:
“The study provided evidence that children who are EmA positive have a celiac-type disorder and benefit from early treatment despite normal mucosal structure, indicating that the diagnostic criteria for celiac disease should be re-evaluated.”
Why might that be?
It could be because:
- we simply don’t know everything about coeliac disease yet,
- it was early stages and the damage hadn’t occurred yet,
- it might be because, by necessity, they have to take patches from different parts of the bowel and may have happened to get OK patches,
- it could be that the damage is in the duodenal ‘bulb’ only,
- it could be that the microscope being used is not powerful enough – electron microscopes have found damage where none was seen previously,
- and it may be that non-specialists could miss the damage where a gut specialist might see some.
Clearly, then, relying on biopsy alone is not necessarily the right thing. Of course, it is always best to have it but don’t rule coeliac disease out if yours shows up nothing.
So, what should you do?
I think it comes down to a mixture of tests, namely:
- blood tests for gliadin antibodies (IgG and IgA and total IgA, the latter because if your total IgA score is low, then the anti-gliadin IgA score is likely to be low too, thus skewing the results)
- blood tests to look for tissue damage – DGP (deaminated gliadin peptides) appears to be the best and some experts think this should replace the biopsy,
- genetic markers (HLA DQ2 and DQ8 are pretty conclusively found in coeliacs),
- and symptom picture/case history.
It is an amalgamation of these that will confirm coeliac disease in my opinion: I don’t think it is wise necessarily to rely on one test result.
If you get a positive to the anti-gliadin IgG antibody, it shows that some kind of immune reaction is going on and to dismiss that out of hand (this test is not as well thought of now as it was, regrettably) is to ignore a physiological process going on. Just because it doesn’t fit the current diagnostic picture doesn’t mean it isn’t happening. My view is that if the IgG test is positive, there is something not right with gluten, whatever that process might be. A DGP test should also be done then to look for tissue damage indicators and a biopsy to confirm. If all comes back negative, look for non-coeliac gluten sensitivity via genetic markers. If DQ2 or DQ8 come up and you feel better off gluten, that’s the info you really need.
That’s my opinion anyway, and I hope it helps. Happy Awareness Week. More tomorrow.
For more info and where to get tests, check the Tests page.