How Gluten Sensitivity Is Diagnosed

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Medical testing

Medical research lends support to the idea that non-celiac gluten sensitivity is a real condition. However, not all physicians agree on its existence; and there's no consensus on how to actually test for gluten sensitivity.

If you suspect you might be sensitive to gluten, you actually have a couple of options that might shed some light on your condition. What's more, there is even a test you can obtain yourself without your physician being involved.

Remember though, none of these testing options definitively prove that you have gluten sensitivity—and they probably will not provide a diagnosis your doctor will accept. However, these gluten sensitivity tests may provide you with evidence that your body is mounting a response to gluten. In this case, a gluten-free diet could help control your gluten sensitivity symptoms.

Keep in mind, most physicians recommend you undergo celiac disease testing first if you suspect you are reacting to gluten. However, if your celiac disease test results are negative, these gluten sensitivity tests might provide useful information.

At-Home Testing

Some patients who believe they are reacting to gluten turn to EnteroLab gluten sensitivity testing. EnteroLab, a Dallas-based medical laboratory specializing in the analysis of "intestinal specimens" (or stool samples) for food sensitivities, offers a direct-to-consumer screening test for gluten sensitivity. After having a positive test, many patients removed gluten from their diets and subsequently reported relief from their gluten sensitivity symptoms.

However, EnteroLab's testing protocol, developed by gastroenterologist Dr. Kenneth Fine, has yet to undergo outside scrutiny and verification. What's more, Dr. Fine has come under considerable criticism from other physicians and from people in the celiac/gluten-sensitive community for failing to publish his research and results.

Consequently, few physicians will accept EnteroLab testing as proof of gluten sensitivity.

Enterolab's stool testing looks for antibodies to gluten directly in your intestinal tract. Dr. Fine said in an interview that this approach looks for the antibodies where the actual reaction is taking place—in your intestines—as opposed to in your bloodstream, where they may be less concentrated. He also said it is ridiculous to think gluten, which he believes is a powerful antigen, only can cause celiac disease, and not other symptoms unrelated to celiac's villous atrophy.

Labs and Tests

Before gluten sensitivity can be diagnosed, celiac disease must be ruled out. Consequently, before performing the endoscopy and biopsy that verifies celiac disease, physicians generally use a panel of celiac blood tests to look for the antibodies that signal the condition. There is some evidence that two of those tests—the AGA-IgA and the AGG-IgG—could indicate non-celiac gluten sensitivity.

AGA stands for "anti-gliadin antibodies," or antibodies your body makes against gliadin, a part of the gluten molecule. IgA and IgG are different forms of immunoglobulin, antibodies made by your body to fight foreign invaders. If AGA-IgA or AGA-IgG are present in your blood, it means your body is making antibodies against the gluten molecule—in other words, it views the molecule as a threat.

Elevated AGA-IgG levels are found in about 10 percent of the overall population and frequently are seen in other autoimmune diseases, such as type 1 diabetes, autoimmune thyroid disease, autoimmune hepatitis, and inflammatory bowel diseases.

Gluten sensitivity research published by the University of Maryland's Center for Celiac Research found that almost half of diagnosed gluten-sensitive patients tested positive for AGA-IgA or AGA-IgG, indicating their immune systems were reacting to gluten. Other physicians, including pediatrician and gluten sensitivity researcher Dr. Rodney Ford in New Zealand, also use the AGA-IgG test to screen for gluten sensitivity.

However, Dr. Alessio Fasano, head of the University of Maryland research center, told me in an interview that the AGA-IgA and AGA-IgG blood tests only serve "as surrogates. There is no specificity there." The fact that about half of gluten sensitivity patients tested negative for AGA-IgA and AGA-IgG antibodies makes those two tests much less useful as tests for gluten sensitivity, he says.

Differential Diagnosis

Generally speaking, when it comes to food sensitivities, celiac disease, gluten sensitivity, wheat allergy all fall into the same category. However, there also are some important differences. For instance, celiac disease is a genetic, autoimmune disease that damages the lining of the small intestines and can lead to malabsorption of nutrients.

Meanwhile, a wheat allergy is an immune system response to the proteins in wheat. When a person has a food allergy to wheat, their body's immune system sees the proteins in wheat as invaders and initiates an allergic response, which can result in hives, swelling of the lips and throat, and in extreme cases anaphylaxis.

Finally, there are some connections between gluten sensitivity and irritable bowel syndrome that will need to be explored by your doctor as well. For this reason, it is extremely important that you talk to your doctor about your symptoms if you feel you are reacting to gluten. Gluten sensitivity can only be diagnosed after ruling out celiac disease and food allergies.

A Word From Verywell

At the moment, physicians who are diagnosing gluten sensitivity may do so based on results from the AGA-IgA and AGA-IgG blood tests, Enterolab testing, or diets that exclude and then reintroduce gluten. However, none of these options has been validated by independent research. Testing for gluten sensitivity is in its infancy at the moment. If medical researchers can that the condition does exist, it is likely that better, more accurate options will be developed in the future.

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Article Sources

  • "Celiac Disease, Non-Celiac Gluten Sensitivity Or Wheat Allergy: What is the Difference?" Gluten Intolerance Group, 2015.

  • A. Fasano et al. "Divergence of Gut Permeability and Mucosal Immune Gene Expression in Two Gluten-Associated Conditions: Celiac Disease and Gluten Sensitivity." BMC Medicine, 2011.

  • Fasano A. et. al. "Spectrum of Gluten-Related Disorders: Consensus on New Nomenclature and Classification. BMC Medicine, 2012.

  • J. Biesiekierski et al. "Gluten Causes Gastrointestinal Symptoms in Subjects Without Celiac Disease: A Double-Blind Randomized Placebo-Controlled Trial." American Journal of Gastroenterology.