Coeliacs may soon no longer need to eat large amounts of gluten – the very thing suspected of making them sick – to get an accurate diagnosis.
Australian researchpublished on Tuesday in the journal Gastroenterologyshowed a blood test for gluten-specific T cells had a high accuracy in diagnosing coeliac disease, even when no gluten was eaten.
Around 1% of people in western countries have coeliac disease, an autoimmune condition in which gluten causes an inflammatory reaction in the small bowel.
Currently, every approved method to diagnose it requires people to eat gluten, the paper said.
Current testing methods – blood tests or a gastroscopy – require weeks of a person eating gluten, while often enduring symptoms such as diarrhoea, abdominal pain and bloating.
Despite the importance of early diagnosis, the researchers said many people are deterred because they do not want to get sick from the tests.
More than one in two cases of coeliac disease are either undiagnosed or diagnosed late, prior research has shown.
“There are likely millions of people around the world living with undiagnosed coeliac disease simply because the path to diagnosis is difficult, and at times, debilitating,” said Assoc Prof Jason Tye-Din, a senior author of the paper and head of the Coeliac Research Laboratory at the Walter and Eliza Hall Institute of Medical Research (WEHI) in Melbourne, Australia.
The new research could be a “game-changer”, helping address “one of the biggest deterrents in current diagnostic practices”, Tye-Din said.
The study evaluated the potential of a blood test to measure an immune marker interleukin 2 (IL-2). In 2019 WEHI researchers discovered that marker spiked in the bloodstream of coeliacs shortly after they ate gluten.
Researchers analysed blood samples from 181 volunteers between the ages of 18 and 75 recruited at Royal Melbourne hospital. These included 75 people with coeliac disease who had been on a gluten-free diet for at least a year, 13 with active, untreated coeliac disease, 32 with non-coeliac gluten sensitivity and 61 controls who did not have coeliac disease nor gluten sensitivity.
Using a new diagnostic system developed with Novoviah Pharmaceuticals, participant blood samples were mixed with gluten to see if the IL-2 signal appeared.
They found the test detected the condition with up to 90% sensitivity and 97% specificity – even in patients following a strict gluten-free diet, the lead author, Olivia Moscatelli, who was diagnosed with coeliac disease at 18, said.
Novoviah Pharmaceuticals was an industry partner on the study, but played no role in the execution or interpretation of the research, authors said. The company aims to get the test into clinical use within two years, Tye-Din said.
The researchers acknowledged the limitations of the study in that it only involved participants from one centre with relatively small subgroup sizes, and that children and patients on immunosuppressants were not assessed.
Several researchers had advisory, directorship and shareholder roles within various pharmaceutical companies declared under conflict of interests.
Prof Peter Gibson, a gastroenterologist from Monash University, said further studies were needed, but “the science is of high quality, the numbers of people tested is large, their underlying conditions well described and the results are very impressive”.
“The test technically is very simple so it can readily be adapted to a routine laboratory test,” Gibson said.
He called it a “genuinely major step forward in the diagnosis of coeliac disease at least in clinically uncertain circumstances”.
Assoc Prof Vincent Ho, a gastroenterologist at the Western Sydney University’s School of Medicine, said “the test is very new and it needs to be validated across other laboratories and be cost-effective compared to current tests before it can be used in clinical practice”.
Ho said one of the most accurate tests currently used to assess coeliac disease is the anti-endomysial antibody test, with 98% sensitivity and 98% specificity.
Ho noted the study’s small sample size and that it would be important the results be replicated in other larger studies in other centres.
“The research … showed that in patients with coeliac disease a single dose of gluten (10 grams or the equivalent of four slices of wheat bread) was able to result in an immune reaction that could be detected on a blood sample in the lab,” Ho said.
“This means in theory that coeliac disease could be diagnosed without the need for weeks of exposure to gluten.”
But, Ho said, because the test assesses an immune response to gluten, this means that people on immunosuppressive drugs may not register a reaction.