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Gluten Intolerance Test

By Sarah

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While the media, restaurants and grocery stores are inundated by the hype surrounding the gluten-free diet, at the core of this matter lies several serious and difficult-to-diagnose forms of gluten intolerance. And despite what you might have heard (or even been told by your doctor), testing for a gluten intolerance is not a simple cut and dry matter.

Use the following lesson index to skip straight to any section:


  • What Is Gluten?
  • How Many Forms of Gluten Intolerance Exist?
  • Understanding Specificity and Sensitivity In Blood Tests
  • Clinical Gluten Intolerance Tests
  • Why Doctors Want You Tested Before You Go Gluten-Free
  • Blood Panels That Might Suggest A Problem
  • Genetic Testing For Celiac Disease
  • Celiac Disease Is More Common Than Most Doctors Realize
  • Allergy Testing
  • What You Need to Know
  • Take The Quiz

What Is This Pesky Protein Composite?

Gluten is a protein composite — we call it a composite because it actually contains several proteins — found in the triticae family of grassy grains; the most common and potent forms are found in wheat, barley and rye. It provides dough its unique elasticity and strength, and gives baked goods form and texture.

Even if you avoid these grains, this pesky protein composite is added to so many products that it can be very difficult to completely remove it from your diet.

To better understand gluten and to learn just how pervasive it is in the western diet, see the following lesson: What Is Gluten?

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How Many Forms of Gluten Intolerance Exist?

This surprises some people (even some doctors, unfortunately), but there is more to gluten intolerance than celiac disease. While it is still considered the most serious medical condition among them, celiac disease is only one of several significant medical conditions triggered by the consumption of this troublesome protein composite.

  • Celiac Disease
  • Non-Celiac Gluten Sensitivity (NCGS)
  • Wheat Allergy
  • Dermatitis Herpetiformis
  • Gluten Ataxia

Along with gluten ataxia, a growing number of gluten-sensitive idiopathic neuropathies are being diagnosed. Collectively medical researchers now refer to these conditions as gluten-related disorders.

Unfortunately, each of these conditions require a different means for diagnosis and with two of them, NCGS and gluten ataxia, doctors and researchers haven’t yet agreed upon a consistent and accurate way to perform diagnosis.

In addition, one form of gluten intolerance, dermatitis herpetiformis, requires a skin biopsy, not blood work. Also, doctors and researchers haven’t yet agreed on how to identify a non-celiac gluten sensitivity in a consistent and accurate manner, other than to rely on a diagnosis by deduction.

In other words, if a gluten challenge reveals a problem with gluten but the patient tests negative for both celiac disease and a wheat allergy, then the patient will be diagnosed as non-celiac gluten sensitive (NCGS).

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Understanding Specificity and Sensitivity In Blood Tests

Different conditions rely on tests with different degrees of specificity and sensitivity. These terms are important to understand:

Specificity is defined by what possible conditions can cause a positive result for a test. If only one single condition or disease can cause a positive result, than that test is considered 100% specific to that condition.

But if more than one condition might change the antibodies measured by the test, than it is not a 100% specific test.

Sensitivity is defined by how often a test identifies people with a condition. Some tests will only show a positive result for 90% of people who take the test. So that test would be considered 90% sensitive.

Unfortunately, it isn’t very common for tests to be 100% specific and 100% sensitive. This is why most blood tests involve a combination of tests. Sometimes the result is determined by both a combination of tests and the doctors interpretation of your overall medical profile.

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Clinical Gluten Intolerance Tests

In the case of celiac disease, we now have 4 different established blood tests to help identify it:

  • Deamidated Gliadin Peptides (DGP)
  • IgA and IgG Antigliadin Antibodies (AGA)
  • IgA Endomysial Antibodies (EMA)
  • tgG Tissue Transglutaminase Antibodies (tTG)

In addition, the following test is almost always ordered to identify patients whose test results will be skewed due to an IgA deficiency:

Total IgA antibodies (To measure for IgA Deficiency)

None of these are 100% specific or 100% sensitive, which is why a doctor experienced in diagnosing celiac disease and a non-celiac gluten sensitivity will order several of these tests.

Since none of these can give you a 100% accurate answer, your doctor will consider your lab results and determine if you need an endoscopy with biopsy. Doctors often use more than the lab results to make this decision: your symptoms, medical history and family history are all taken into consideration.

An intestinal biopsy is considered, by most doctors and researchers, to be the only definitive test for celiac disease. It is often referred to as the “gold standard” for celiac disease diagnosis.

If your doctor decides to do a blood panel for celiac disease, try to make sure he or she uses the most recent and accurate tests: Deamidated Gliadin Peptides and IgA Endomysial Antibodies.

In addition, the Total IgA Antibody test should always be taken to determine if you are IgA deficient. If you are IgA deficient, they will need to read the results of your other tests differently (and in some cases the tests will not provide useful results).

If your total IgA is low enough, your doctor may run a IgG tissue transglutaminase antibody test instead.

Another test popular among laymen online is the Fecal Anti-Gliadin Antibodies test (fAGA), most prominently conducted and promoted by the Enterolab. However, corroborating research in peer review journals hasn’t been done yet. Anecdotal evidence among my readers suggests a high rate of success with this test, but again note that you may test negative if you’ve already subscribed to a strict gluten-free diet. Also, most doctors and researchers I’ve consulted don’t believe this test is either specific or sensitive enough to be relied upon to diagnose either celiac disease or non-celiac gluten sensitivity.

One last test to mention is the screen for Antireticulin Antibodies (ARA). At one time this was a common blood test to order when diagnosing celiac disease. However, doctors and researchers now agree that this celiac disease blood test is obsolete.

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Why Doctors Want You Tested Before You Go Gluten Free

A gluten-free diet can reduce the biomarkers doctors use to confirm the presence of celiac disease, making a complete diagnosis very difficult. Doctors don’t like to have an inconclusive diagnosis because celiac disease is a serious medical condition that should be in your official medical profile.

Basically, once you remove gluten from your diet, your body produces less of the harmful antibodies triggered by gluten and the villi along the wall of your small intestine begin to heal. If your villi are healthy and you don’t have raised antibodies in your blood, you may test negative for celiac disease. So if you take steps to eliminate a gluten intolerance on your own, you may also make it difficult to have your condition accurately diagnosed.

Because patients are understandably wary about eating food they’re sure is hurting them, doctors and researchers are trying to make testing more sensitive so that a gluten challenge can be shorter and less intimidating.

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Blood Panels That Might Suggest A Problem

The following tests are often conducted by thorough doctors when evaluating patients for a non-celiac gluten sensitivity, a gluten intolerance or a verified case of celiac disease:

  • Stool Fat test, to determine malabsorption level (test for Steatorrhea).
  • Complete Blood count (CBC), to determine anemia.
  • Erythrocyte Sedimentation Rate (ESR) to look for inflammation.
  • C-Reactive Protein (CRP) to further watch for chronic inflammation.
  • Vitamins A, D, E and K (the fat-soluble vitamins) to check for vitamin deficiency relating to malabsorption in the proximal small intestine.
  • Comprehensive Metabolic Panel (CMP) to analyze protein, calcium and electrolyte levels as well as to check liver and kidney functions.

I’ve also had readers inform me that they’ve had doctors test and confirm a Non-Celiac Gluten Sensitivity (NCGS) with the gliadin IgG non-deamidated antibody test. I think many doctors and researchers would consider this too simple and narrow, but at least some anecdotal evidence suggests otherwise.

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Genetic Testing For Celiac Disease

The most established genetic test is specific to celiac disease and not necessarily for a wheat allergy, a non-celiac gluten sensitivity or a broader intolerance. But it can help either verify the presence of celiac disease or identify people who may be predisposed to developing celiac disease. Because it can be done in a non-invasive manner (a saliva swab is often enough), this celiac disease genetic test is often done for at-risk children.

The test looks for the HLA-DQ2 and HLA-DQ8 genes. If one or both genes are present and the patient has a family history of digestive concerns, the individual is at a greater risk of developing celiac disease at some point in his or her life.

Please note, however, that it is still possible to have these genes and not develop celiac disease. In fact, around 35% of the general population has these genes while around 1% of the population has celiac disease. That means millions of people have the so-called celiac gene but do not have celiac disease.

So this test is usually either to take preliminary steps in identifying and helping at-risk individuals (people who have celiac disease in their immediate family) or to help confirm a diagnosis begun with some of the tests listed earlier in this lesson.

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Celiac Disease Is More Common Than Most Doctors Realize

Many doctors still consider celiac disease to be relatively rare (although current gluten intolerance statistics may suggest otherwise), so if your doctor doesn’t bring up the possibility of celiac disease, you need to speak up and be your own health advocate.

According to recent research published in the BMC Journal, “The mean delay to diagnosis from the first symptoms was 9.7 years, and from the first doctor visit it was 5.8 years.” What this means is that, on average, it is taking doctors nearly six years to properly diagnose celiac disease after a patient first visits his or her doctor complaining about symptoms. Right now, millions of people all over the world are walking around with celiac disease but don’t realize it.

In addition, please note that just because you test negative for celiac disease does not mean with certainty that you still do not have some form of gluten intolerance. It also does not preclude the possibility of a wheat allergy. For more on these distinctions, please read gluten intolerance symptoms.

Note that as of March 2011, a gluten sensitivity may exist as its own clinical entity, separate from celiac disease. Many doctors and researchers currently believe the only way to distinguish this form of gluten intolerance from celiac disease is to do an intestinal biopsy. This new condition has become widely known as NCGS, for non-celiac gluten sensitive.

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Allergy Testing

This is usually a skin prick test, which allows a doctor to test for a variety of food and other allergies at once. If the skin prick test comes back positive for a wheat allergy, an elimination diet is the next step. If it does not come back positive, more testing is done to rule out other illnesses or conditions that could cause similar symptoms.

An allergy is a type 1 hypersensitivity, not an autoimmune disease, so it is possible to have a wheat allergy but not have celiac disease, and vice versa.

If you’re looking for a gluten allergy test, such a thing doesn’t really exist. You can test for celiac disease, a wheat allergy and for dermatitis herpetiformis, but there is no widely accepted gluten sensitivity or allergy test.

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What You Need to Know

Diagnosing celiac disease is not simple. To assume a single blood test will accurately diagnose your condition is to greatly underestimate the process.

In addition, you can test negative for celiac disease but still have one or more of several different forms of gluten intolerance, including:

  • Non-Celiac Gluten Sensitivity
  • Wheat Allergy
  • Dermatitis Herpetiformis
  • Gluten Ataxia

Each of these conditions require a different mode of diagnosis. Dermatitis herpetiformis requires a skin biopsy, not blood work.

An endoscopy with biopsy is still considered the gold standard for diagnosing celiac disease.

The most recent and accurate blood tests available are the tests for Deamidated Gliadin Peptides and IgA Endomysial Antibodies, so if your doctor decides to do blood work, make sure these are done.

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Take The Quiz!

How Well Do You Understand Gluten Intolerance Diagnosis?

Are you sure you understand what it takes to diagnose gluten intolerance? Take the following quiz and find out.
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Congratulations - you have completed How Well Do You Understand Gluten Intolerance Diagnosis?.

You scored %%SCORE%% out of %%TOTAL%%.

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Your answers are highlighted below.
Question 1
True or False: Having a wheat allergy is the same thing as having celiac disease.
A
False
B
True
Question 1 Explanation: 
An allergy is a type 1 hypersensitivity, not an autoimmune disease, so it is possible to have a wheat allergy but not have celiac disease, and vice versa.
Question 2
Why do doctors often want you to continue or resume eating gluten before you are tested for celiac disease?
A
Because they believe celiac disease is really rare and doctors want you to obtain the important nutrients obtained from gluten-containing foods.
B
Because you should only stop eating gluten if you have verified that you have the so-called "celiac" genes.
C
Because if you do not consume gluten for a significant period before you are tested for celiac disease, the biomarkers the tests use to identify celiac disease will not be present.
Question 2 Explanation: 

This is a challenging and sometimes controversial aspect of testing for celiac disease. If you believe gluten is hurting you, you desperately want to stop eating it. But if you stop eating it for too long before you are officially tested for celiac disease, you may not receive an accurate test and diagnosis.

Doctors want an accurate and complete diagnosis because celiac disease is a very serious disease. Knowing for certain that you have it will provide a more complete and accurate medical profile for all doctors and surgeons you see for the rest of your life.

In addition, doctors need to know if they should look for other causes of your ailments if they determine with confidence that gluten is not the cause of your problems. While I've read some compelling arguments against this stance, please appreciate that this is currently the technically accurate stance according to most medical professionals.

One last point: If you know for certain you have a life-threatening disease, you may be more motivated to be strict and vigilant in living a gluten-free life. Too often, people who self-diagnose aren't vigilant enough about removing gluten from their diet.

Question 3
What deficiencies most often occur first when you develop celiac disease?
A
Vitamins A, D, E and K
B
Vitamin B
C
Vitamin C
D
Vitamins B and C
Question 3 Explanation: 

While this will vary with every individual, statistically the most common vitamin deficiencies tend to be the fat-soluble vitamins absorbed in the proximal intestine -- the upper part of the small intestine.

This is because this is where the inflamed intestinal lining caused by celiac disease tends to first appear, and when your intestinal lining becomes inflamed and its villi is damaged, it is less able to absorb nutrients from your food.

Question 4
True or False: Most doctors and celiac researchers accept the Fecal Anti-Gliadin Antibodies test (fAGA) as an accurate substitution for the celiac blood panel followed by an endoscopy and small intestine biopsy.
A
True
B
False
Question 4 Explanation: 

This statement is false because most doctors and celiac researchers do not believe this is an accurate way to diagnose celiac disease.

In addition, despite the claims made by labs promoting this test, at this point there is little corroborating research in peer review journals.

I know a few of my readers have been very happy with the results they experienced while working with labs like Enterolab and I've mentioned them on my site before, but when I consult reputable medical professionals on this matter, they consistently advise me to not promote the fAGA test as an acceptable substitution for endoscopic biopsy.

The endoscopic biopsy remains the gold standard for accurate celiac disease testing.

Question 5
When someone suffers from celiac disease or a gluten sensitivity, it is common for that individual to suffer from the following vitamin and mineral deficiency:
A
Vitamin E
Hint:
Well, you're partially right!
B
Vitamin B12
Hint:
Well, you're partially right!
C
Iron and Calcium
Hint:
Well, you're partially right!
D
All of these.
E
Vitamins A, D, E and K (the fat-soluble vitamins)
Hint:
Well, you're partially right!
Question 5 Explanation: 
All of these vitamins and minerals may become deficient if you suffer from an untreated gluten sensitivity. Your intestinal tract simply can't process and absorb your food properly, so you absorb much less of its nutrients.
Question 6
Why is it such a good idea to empower yourself with an understanding of gluten intolerance testing and celiac disease before you go to your doctor? (More than one answer is correct here.)
A
Because you shouldn't trust your doctor.
Hint:
I know many people feel this way, but if you really don't trust your doctor, find another doctor. You really shouldn't diagnose yourself using the Internet and gluten intolerance is a serious matter requiring real medical attention.
B
Because a negative test for celiac disease only precludes one of several possible forms of gluten intolerance.
C
Because the test results your doctor will provide you can be difficult to understand.
D
Because too many doctors either think celiac disease is more rare than it actually is or they look to other conditions or diseases as the causes of celiac disease symptoms.
Question 7
If you take a blood test for celiac disease and your test is negative, which of the following conditions can you still have?
A
Dermatitis Herpetiformis
Hint:
You're partially right...
B
Gluten Ataxia
Hint:
You're partially right...
C
Non-Celiac Gluten Sensitivity
Hint:
You're partially right...
D
All of these.
E
Wheat Allergy
Hint:
You're partially right...
Question 7 Explanation: 

All of these conditions can exist without celiac disease, though gluten ataxia and dermatitis herpetiformis most often occur in conjunction with celiac disease.

The antibody test for Celiac Disease is only used to diagnose celiac disease itself. All these other conditions can exist even when celiac disease is not present.

Question 8
What is Steatorrhea and how does it relate to detecting gluten intolerance?
A
When you have steatorrhea, you have too much fat in your feces, which means your intestines are not properly absorbing fats from food your body is trying to digest.
B
This is a condition related to a deficiency of healthy fats in your diet.
C
When you have steatorrhea, you have too much fat in your feces, which means you have too much fat in your diet.
D
It's a form of strep throat and it indicates a compromised immune system.
Question 8 Explanation: 

Steatorrhea manifests as foul-smelling feces with a grayish hue and a tendency to float more than a healthy bowel movement. It indicates poor absorption of fats and may suggest poor absorption of other nutrients as well.

When Steatorrhea occurs, your doctor should consider further testing for celiac disease or a gluten sensitivity as poor absorption can occur as a result of intestinal damage or inflammation as may occur with celiac disease.

Question 9
True or False? It is possible to have a serious gluten sensitivity even if you test negative for celiac disease.
A
True
B
False
Question 9 Explanation: 

A person who tests negative for celiac disease can still experience a wide range of conditions resulting from gluten consumption.

A wheat allergy, non-celiac gluten sensitivity (NCGS), dermatitis herpetiformis and gluten ataxia may all occur in individuals who do not have celiac disease.

Question 10
What should you do if you take a genetic test and discover you have the celiac genes, HLA-DQ2 and HLA-DQ8?
A
Celiac disease is incredibly rare, even for people with the celiac genes, so just play it safe by eating less gluten.
Hint:
There is no "play it safe" when it comes to gluten.
B
Immediately stop eating gluten as this genetic test proves you have celiac disease.
C
Before you stop eating gluten, see your doctor, show him or her your positive test for the celiac genes, and request the appropriate celiac disease tests (blood panel and depending on your doctor's advice, an intestinal biopsy).
Question 10 Explanation: 

About 35% to 40% of all people have one or both of these genes and about 1% of all people have celiac disease, so having these genes does not mean you have celiac disease. In fact, a majority of people with these genes do not have celiac disease.

However, because having them does significantly increase your risk, you should discuss the matter with your doctor, or preferably a gastroenterologist experienced with diagnosing and treating celiac disease.

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Filed Under: Celiac Disease, Food Allergies, Non-Celiac Gluten Sensitivity Tagged With: allergen test, celiac disease checklist, dermatitis herpetiformis, genetics, gluten intolerance diet, gluten intolerance in children, gluten intolerance test, gluten-related disorders, intestinal biopsy, NCGS, steatorrhea, tissue transglutaminase, type 1 hypersensitivity, villous atrophy, wheat allergy

Meet Sarah Patrick

Sarah Patrick
Hi, I'm Sarah Patrick. If you're concerned about the role of gluten in your life, I'm here to help you find clarity and confidence through better understanding. Read More »

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