Celiac disease diagnosis could be simplified for those already on a gluten-free diet

January 24, 2018

Celiac disease diagnosis could be simplified for those already on a gluten-free diet

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Gluten sensitive patients reluctant to eat gluten again could be spared a return to symptoms by a new test under study in Norway

By Amy Ratner, Medical and Science News Analyst

If you’ve gone on a gluten-free diet without a diagnosis and would like to find out if you have celiac disease, a blood test now under study could eliminate the need for a gluten challenge and biopsy.

Researchers at Oslo University Hospital in Norway are researching a blood test that can detect T-cells that react to gluten whether someone is consuming gluten or not. This immune reaction occurs only in those who have celiac disease.

T-cells – White blood cells that function as the body’s disease fighting soldiers

The test “identifies patients with and without celiac disease with a high level of accuracy, regardless of whether the individuals are on a gluten-free diet,” researchers conclude, though the authors note the test needs to be validated in a larger study.

When given to study participants who were following the gluten-free diet, the test correctly detected celiac disease in 97 percent of cases and correctly ruled it out in 95 percent. These participants also all had the gene most commonly associated with celiac disease, HLA-DQ2.5.

Sensitivity – The ability of a test to correctly classify a person as having a disease

Specificity – The ability of a test to correctly classify a person as not having a disease

The test can “replace (the) gluten challenge followed by (the) biopsy for exclusion of celiac disease in a sizable majority” of patients who have the HLA_DQ2.5 gene, the study says. While, most celiac disease patients have HLA-DQ2 or HLA-DQ8 genes, those who have the genes don’t necessarily have celiac disease. The genes are found in about 30 percent of the general population and only about 5 percent of those will develop celiac disease, according to the University of Chicago Celiac Disease Center.

Ruling out celiac disease

The new blood test would be most effective in ruling out celiac disease for gluten sensitive patients who have put themselves on the gluten-free diet, according to study authors. If these patients get a positive result, they would not need further testing. In a clinical setting, the new test would offer a “faster, more sensitive and symptom-free” method of diagnosis compared to a two- to 12-week gluten challenge followed by a biopsy, the study says.

In analyzing how the test would work best, researchers pointed to a previous study that showed only about 10 percent of gluten sensitive patients with the needed genes and following a gluten-free diet have celiac disease, increasing the probability that the new blood test more accurate in ruling out celiac disease.

Gluten sensitive patients who get positive tests results from the new blood test would still be advised to go through the challenge and biopsy to get an accurate diagnosis, according to the study. “Hopefully, in the future the performance of (the test) can be further improved, allowing the diagnosis to be made directly without the need for an oral gluten challenge,” the authors wrote.

The study included 62 participants with celiac disease on the gluten free diet, 60 of whom tested positive using the new blood test. Meanwhile, 18 of the 19 participants who were following the gluten-free diet because of gluten sensitivity tested negative.

The new blood test is still in experimental stages, and currently, all patients who have gone on the gluten-free diet have to eat gluten again for an extended period and then have a biopsy to find out if they have celiac disease. Neither available anti-tissue transglutaminase immunoglobulin A (tTG IgA) blood tests nor the biopsy are accurate when someone has eliminated gluten, the trigger for celiac disease, from the diet.



Resistance to eating gluten again

Many patients are reluctant to eat gluten again because they are fearful it will cause a return of the gastrointestinal and other symptoms that caused them to adopt the diet in the first place. In some cases, patients put themselves on the diet and in others they are advised to do so by physicians even though celiac disease tests then become inaccurate.

Celiac disease researchers are working on ways to shorten or eliminate the gluten challenge to address patients’ concerns about eating gluten again before they can be correctly diagnosed. It’s estimated that 83 percent of celiac disease patients remain undiagnosed, some of whom have identified themselves as gluten sensitive and gone on the gluten-free diet on their own.

For example, ImmusanT, a Massachusetts biotechnology company, is developing a blood test that can detect the earliest effects of gluten and would require those already on the gluten-free diet to eat gluten only one time in order to be accurately tested for celiac disease.

Read more: Gluten-free labeling of drugs in the news

In addition to diagnosis for patients who’ve gone on the gluten-free diet, the Oslo University researchers theorize their new blood test could be a “new and less invasive supplement to existing tests” for those who are still eating gluten.

For most patients in this group, positive tTG blood tests followed by the biopsy are likely to continue as the diagnostic “gold standard for celiac disease,” but in cases where a biopsy is not possible, the new test could potentially be used for diagnosis.

Ten study participants with celiac disease who were still eating gluten were tested and correctly identified 100 percent of the time. These patients had positive results from tTG blood tests and were waiting for the biopsy to be performed so they had not started the gluten-free diet.

The new blood test might also be used to help identify what’s sometimes called “potential celiac disease,” where a patient has positive results on standard blood test, but negative biopsy results. Used with tTG tests, positive results of the new blood test could help predict when celiac disease might develop and open a window for early therapeutic intervention, according to the study.

 


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