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Celiac Disease Test

The first step along the journey to addressing symptoms and healing the body is a proper diagnosis. This article will discuss the process for getting a celiac disease test, including the different types of testing and the pros and cons of each. 

What is Celiac Disease?

Celiac disease is an autoimmune disorder characterized by a reaction to ingested gluten in genetically predisposed individuals. The immune response to gluten damages the villi of the small intestine, leading to malabsorption of nutrients and a number of other health complications. 

Celiac disease is sometimes confused with a wheat allergy or non celiac gluten sensitivity, but these are different conditions.

Wheat allergy

A wheat allergy causes an immune response in the body when wheat is either ingested (food allergy) or inhaled (respiratory allergy).

An allergic reaction to wheat can manifest with a variety of symptoms that include hives, skin swelling, asthma, allergic rhinitis, abdominal pain, vomiting, acute exacerbation of atopic dermatitis, and exercise-induced anaphylaxis.  

Wheat allergy can be diagnosed with testing from your doctor.  The tests include either skin prick or blood tests measuring IgE response to wheat.

Gluten Sensitivity

Non Celiac Gluten Sensitivity (Gluten Sensitivity) is a condition where individuals experience symptoms similar to those of celiac disease after consuming gluten, but without evidence of villous atrophy occurring in the intestinal lining. The exact mechanism is not fully elucidated, but genetics, history of infection, using certain medications (antibiotics, steroids, NSAIDS, and ARB’s),   altered gut microbiota and low-grade inflammation are all  believed to play a role

In both celiac disease and non celiac gluten sensitivity, gluten consumption triggers symptoms. The symptoms of gluten exposure can vary greatly from person to person which can make a diagnosis challenging. In addition, symptoms extend far beyond the digestive concerns that are most commonly discussed with respect to celiac disease,. Common symptoms include the following:

The Process for Celiac Disease Testing

The process for getting a celiac disease test may vary slightly depending on your healthcare practitioner. 

For many providers, blood tests are the first step in a diagnosis of celiac disease. These blood tests measure your body’s response to gluten.  Before getting into the specifics of the tests, it is important to understand that a few things first.

  • Total immunoglobulin A (Total IgA): Immunoglobulin A (IgA) is an important part of the immune system that helps protect the body from things that could harm it, like bacteria and viruses. However, high Immunoglobulin A (IgA) levels can mean that the immune system is working extra hard to protect the body from other substances it finds harmful. This may include bacteria and viruses, but it can also be a result of inflammation or an autoimmune condition like celiac disease. It is a helpful marker, but not specific to celiac disease. 
  • Tissue transglutaminase IgA (IgA-tTG): in those with celiac disease, the body mistakenly thinks that gluten is a foreign invader, so it makes antibodies that attack an enzyme in the intestines called tissue transglutaminase (tTG).
  • IgA anti-endomysial antibodies (IgA-EMA): IgA anti-endomysial antibodies are a more specific and sensitive blood marker for celiac disease. They are found in 90% of celiac patients. 
  • Anti-gliadin antibodies (AGA): Anti-gliadin antibodies are produced in response to gliadin, a prolamin found in wheat. Since gliadin is only found in wheat, not barley, rye or oats, this may be seen as a less precise test. However, a study at Tripler Army Medical Center found that while IgA-tTG was found to have a higher positive predictive value for celiac disease than AGA, AGA identified 5 patients (19% of biopsy confirmed celiac disease) that had a negative tTG and would not have been identified by tTG screening alone. Therefore, it can be wise to test AGA in combination with tTG.
  • IgA DGP: This test looks for the level of deamidated gliadin antibodies in the blood. Gliadin is one of the main proteins in gluten. 
  • IgG DGP: Like IgA DGP, immunoglobulin G-deamidated gliadin peptide is reported to be able to detect certain patients who are missed on IgA-tTG tests.

Range of Sensitivity and Specificity and Use of Current Serologic Tests for Celiac Disease

Serologic Study
Sensitivity
Specificity
Application in Clinical Practice
IgA tTg
73.9% – 100%
77.8% – 100%
First-line testing to screen for celiac disease
IgG DGP
80.1% – 96.9%
86.0% – 96.9%
First-line testing for celiac disease in patients with IgA deficiency
IgA EMA
82.6% – 100%
94.7% – 100%
Second-line confirmatory test to screen for celiac disease
IgG tTG
12.6% – 99.3%
86.3% – 100%
Not recommended for routine use because of poor sensitivity compared with IgG DGP
IgA DGP
80.7% -95.1%
86.3% – 93.1%
Not recommended for routine use because of poor sensitivity and specificity compared with IgA tTG and IgA EMA

Leonard, M. M., Sapone, A., Catassi, C., & Fasano, A. (2017). Celiac Disease and Nonceliac Gluten Sensitivity: A Review. JAMA, 318(7), 647–656. https://doi.org/10.1001/jama.2017.9730

However, all of the above blood tests are not 100% reliable as they can easily present false negatives. IgA deficiency is 10-15 times more common in those with celiac disease, therefore contributing to the potential for false negative tTG, anti gliadin antibodies, and EMA IgA based tests. 

If any of the blood test markers do come back high, some practitioners will have a patient try a gluten free diet, while others will move onto further testing with an endoscopy. We discuss the process for endoscopy below.

The process for testing may not be the same for everybody, but it is important to advocate for a comprehensive evaluation in order to get to the root of your symptoms. Don’t let one negative test derail your quest for answers and an accurate diagnosis.

Type of Celiac Disease Testing

There are several different options to test for celiac disease, described below. 

Blood Testing

As discussed above, a blood test checks for certain antibodies. People with celiac disease who eat gluten produce antibodies in their blood because their immune systems view gluten as a threat. It is important to note that you must be on a gluten-containing diet for antibody blood testing. It is also important to note that these types of tests can also be misleading, as they can come back falsely negative. There are several studies that highlight inaccurate results.

A food sensitivity blood test can also be helpful for identifying foods that trigger similar symptoms like bloating, diarrhea, abdominal discomfort, skin issues, brain fog, and more.

Endoscopy

An endoscopy is when a tube is inserted down your throat so that a practitioner can look at your small intestine for inflammation or damage (villous atrophy). They may also take a small biopsy of your intestines. Like blood testing, you must be eating a diet that contains gluten for this test to be accurate. This type of testing is accurate when positive, but missed diagnosis is common. In fact, one study found that endoscopy had low sensitivity (below 50%) in detection of persistent villous atrophy. The authors called for “more-accurate non-invasive markers of mucosal damage in children and adults with celiac disease.” 

A biopsy finding villous atrophy can also be misleading because other things can cause atrophy beyond gluten, such as parasites, glyphosate, non steroidal anti inflammatories (NSAIDS), proton pump inhibitors (PPIs) used traditionally for heartburn, selective serotonin reuptake inhibitors (SSRIs) used for depression and mood disorders, etc.  If you are taking any of these medications, it is important to inform your doctor before scheduling a biopsy so as to avoid the possibility of a false positive test. A more comprehensive list of other causes and contributing factors to villous atrophy and intestinal inflammation can be found in the diagram below:

Medication Induced
Infections
Chemical Exposure
Malnutrition
Food Reaction
Antibiotics
Parasitic
Glyphosate
Anorexia
Food Allergies
NSAIDs
Bacterial
Mercury
B3 Deficiency
Food Sensitivities
Proton Pump Inhibitors
Viral Infections
Cadmium
Vit. A Deficiency
Alcoholic Drinks
SSRI’s
SIBO
Use of Nitrogen Fertilizers on Grains
L-Glutamine Deficiency
Artificial Sweeteners
Chemotherapy
Candida Overgrowth
Persistent Organic Pollutants
Butyrate Deficiency
Emulsifiers
Radiation
Mycotoxins
Protein Deficiency
Food Dyes
Corticosteroids
Iron Deficiency
Meat Glue
Angiotensin Receptor Blockers
Folate Deficiency
Biologics
B12 Deficiency

Pros and Cons of Blood and Endoscopy Testing

The benefit of blood testing is that it is quick, non invasive, and if positive can help a person understand the need to go gluten free.  The downside is that it can be misleading and show false negative results.

Although helpful in determining a celiac diagnosis, endoscopy testing can be misleading because there are other things that can cause villous atrophy beyond gluten.

The downside to both tests is that you must be eating gluten in order to get an accurate test result. Many people who suspect celiac disease have started eating gluten free and have started to feel better. Having to reintroduce gluten can cause a resurgence of symptoms and  further deterioration of health.

Genetic Testing

Genetic testing is a highly accurate look at your genes to understand whether you have a genetic predisposition to reacting to gluten. You do not need to be eating gluten in order to get an accurate test result. Research indicates that clinical manifestations, like those found through blood testing and endoscopy, are not sufficient for a true diagnosis. A genetic test shows a more complete picture. Make sure to get a test that measures for all genes linked to gluten sensitivity (HLA-DQ1/HLA-DQ3) and celiac disease (HLA-DQ2/HLA-DQ8). Some tests only check for genes linked to celiac disease.

Why You Should Take a Celiac Disease Test

Put simply, a celiac disease diagnosis can change your life. This isn’t just because a celiac disease diagnosis involves some lifestyle changes, but because there are risks involved with undiagnosed celiac disease. Some of these risks include the following:

Common Concerns and Misconceptions

One of the most common misconceptions about celiac disease testing is that it is foolproof. As discussed above, celiac disease testing can result in false negatives. If you are having symptoms and/or have a family history of celiac disease and your test is negative, continue onto other testing methods.

Occasionally, people are concerned about discomforts associated with testing. The least invasive testing is genetic testing, which involves a simple swab of your cheek. Blood testing is also minimally invasive, but can be stressful for those who have a fear of blood or needles. Endoscopy is the most invasive testing method, however, you will be sedated and should not feel any discomfort during the procedure. Discuss any fears or concerns about testing with your practitioner.

Conclusion

Accurate testing and diagnosis for celiac disease is critical for your health in both the short and long term. Please feel empowered to seek the appropriate testing and practitioner support that you need and deserve.

Want to start simply? Take the Gluten Sensitivity Test.

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