About the Test
Purpose of the test
Celiac disease antibody tests are primarily used to help diagnose and monitor celiac disease in people presenting with signs and symptoms, including anemia and abdominal pain.
Sometimes celiac testing may be used to screen for asymptomatic celiac disease in those who have close relatives with the disease since about 4% to 12% of them have or will develop celiac disease. Testing may also be ordered for those who have other autoimmune diseases.
What does the test measure?
Celiac disease blood tests measure the number of particular antibodies in the blood. The most common tests include:
- Tissue transglutaminase antibody (tTG), IgA class is the primary, most sensitive, and specific blood test — and the single test preferred by the American College of Gastroenterology and the American Gastroenterology Association for the detection of celiac disease in those over 2 years old. If positive, the test can also monitor the condition and help evaluate the effectiveness of treatment. (Although “tissue” is in the name of this test, it is measured in the blood.)
- Immunoglobulin A (IgA) is usually ordered with the tTG-IgA test to detect IgA deficiency, which occurs in about 2-3% of people with celiac disease. If you have an IgA deficiency, the test for tTG-IgA may be negative even if you have celiac disease (false-negative test results). And if the IgA test shows you have a deficiency, then a test to detect the tTG-IgG class of autoantibodies may be ordered (see below).
- Deamidated gliadin peptide (DGP) antibodies (anti-DGP), IgA or IgG may be used in some people with suspected celiac disease who are negative for anti-tTG, especially children younger than 2. DGP-IgG testing, along with anti-tTG IgG, is recommended by the American College of Gastroenterology for people with low IgA or IgA deficiency. If the anti-DGP test is positive, it may be used to monitor celiac disease.
Tests that are used less often include:
- Anti-endomysial antibodies (EMA) tests for antibodies developed in reaction to the ongoing damage to the intestinal lining; it has been found that tTg is the substance detected in this test. Almost 100% of people with active celiac disease and 70% with dermatitis herpetiformis (another gluten-sensitive condition that causes an itchy, burning, blistering rash on the skin) will have the IgA class of anti-EMA antibodies.
The test, more difficult to do and interpret properly than anti-tTg, is used less often.
- Anti-reticulin antibody (ARA) test is not as specific or sensitive as the other autoantibodies and rarely ordered; it is found in about 60% of people with celiac disease and about 25% of those with dermatitis herpetiformis.
To confirm a diagnosis of celiac disease, an upper gastrointestinal (GI) endoscopy is ordered, and a small intestine biopsy is examined to detect damage to the intestinal villi. However, given the invasive nature and cost of a biopsy, antibody tests are often used to identify those individuals with a high probability of having celiac disease.
When should I get a celiac disease antibody test?
Celiac disease tests are ordered when signs and symptoms suggest celiac disease, malnutrition, or malabsorption. You will usually have one or more symptoms before being diagnosed and treated. The symptoms are often nonspecific and variable, making the disease difficult to spot. For a time, the symptoms may be mild and go unnoticed and then progressively worsen or occur sporadically. The condition can affect different parts of the body.
Digestive signs and symptoms may include:
- Abdominal pain and distension
- Bloody stool
- Chronic diarrhea or constipation
- Greasy, foul-smelling stools
- Lactose intolerance (due to small intestine damage)
Other signs and symptoms may include:
- Iron-deficiency anemia that does not respond to iron supplements
- Easy bruising and/or bleeding
- Bone and joint pain
- Defects in dental enamel
- Fatigue, weakness
- Mouth ulcers
- Weight loss
- In adults, infertility and osteoporosis
In children, celiac disease tests may be ordered when a child exhibits:
- Digestive tract symptoms
- Delayed development
- Short stature
- Failure to thrive
- Weight loss
- Permanent damage to tooth enamel
- Mood changes/anxiety/impatience
About 10% of people with celiac disease have dermatitis herpetiformis. There is also an increased risk for developing intestinal lymphoma, a form of cancer.
If you have celiac disease, even trace amounts of gluten can be harmful. You must pay due diligence when using certain foods, medications, or other non-food products. These might include vitamins, supplements, herbal products, lipstick, toothpaste, and even an envelope and the glue from a stamp.
Initial evaluation requires that you continue to eat foods with gluten for several weeks before testing. Once celiac disease has been diagnosed, one or more antibody tests may be ordered when you have been on a gluten-free diet for some time. This is done to verify that antibody levels have decreased and to verify that the diet has been effective in reversing the intestinal lining damage (this is sometimes still confirmed with a second biopsy).
Asymptomatic people may be tested if they have a close relative — such as a parent or sibling — with celiac disease. Still, testing is not recommended at this time as a screen for the general population.
Usually, genetic HLA testing (Human Leukocyte Antigen) shows a person with celiac disease to have variations in the genes that code for HLA-DQ2.5 or HLA-DQ8. Genetic testing may be ordered if you have unclear or variable serological results. If you are negative for HLA-DQ2.5 and HLA-DQ8, you most likely do not have celiac disease.
Finding a Celiac Disease Antibody Test
How can I get a celiac disease test?
Celiac disease antibody testing is usually performed at a doctor’s office or another medical setting like a hospital or lab. These celiac disease antibody tests are normally requested by a doctor but may be available without orders from your doctor at a walk-in lab.
Can I take the test at home?
Some at-home celiac tests allow you to draw your own blood using the finger prick method and collect the sample, which is then mailed to a lab for analysis. Other tests require you to visit a blood lab. Either way, you should receive results within a few days.
How much does the test cost?
The cost of a celiac disease antibody test will vary depending on factors such as where the test is done and whether you have health insurance. When ordered by a doctor, insurance typically covers the test, although you may have to pay a copay or deductible. Your doctor’s office, lab, and health plan can provide information about any out-of-pocket costs that may be your responsibility.
Taking a Celiac Disease Antibody Test
The celiac disease antibody test usually requires a blood sample, which is usually taken from your arm in a doctor’s office, health clinic, hospital, or lab.
Before the test
Follow your health care practitioner’s instructions. For diagnosis, continue to eat foods that contain gluten for a time period, such as several weeks, before testing. No preparation is necessary for monitoring celiac disease when you have already been diagnosed.
During the test
A blood sample is taken from a vein in your arm. The person taking the sample may tie a band around your upper arm and will clean the area where the needle will be inserted into your skin. A small amount of blood is drawn into a tube. You may feel a slight sting when the needle enters your skin.
The process of taking a blood sample usually takes less than three minutes.
After the test
At a doctor’s office or lab, you will be asked to apply gentle pressure to the site with a bandage or a piece of gauze after the needle is withdrawn. This will help stop bleeding and may prevent bruising. Next, the site will be bandaged. You may resume your normal activities following the test.
A blood draw is a very low-risk procedure. You may have slight bruising at the site where the blood sample was taken.
Celiac Disease Antibody Test Results
Receiving test results
The doctor who ordered your celiac disease antibody test may share the results with you, or you may be able to access them through an online patient portal. Celiac disease antibody test results are usually available within a few business days.
Interpreting test results
|Celiac disease tests and possible results|
|tTG, IgA||Total IgA||tTG, IgG||DGP, IgA||DGP, IgG||Diagnosis|
|Positive||Normal||Not performed||Not performed||Not performed||Presumptive celiac disease|
|Negative||Normal||Negative||Negative||Negative||Symptoms not likely due to celiac disease|
|Negative||Low||Positive||Negative||Positive||Possible celiac disease (false negative anti-tTG, IgA and anti-DGP, IgA are due to total IgA deficiency)|
|Negative||Normal||Negative||Positive||Positive (or not performed)||Possible celiac disease (may be seen in children under 3 years old)|
All positive and indeterminate celiac disease tests are typically followed by an intestinal biopsy to make a definitive diagnosis of celiac disease. About 2%-3% of patients may test negative for serologic studies. If celiac disease is still suspected, a biopsy is generally done.
If you have been diagnosed with celiac disease and eliminate gluten from your diet, the autoantibody levels should fall. But if they do not fall and the symptoms do not diminish, the diet may have hidden forms of gluten that have not been eliminated. Gluten is often found in unexpected places, from salad dressings to cough syrup to the adhesive used on envelopes.
Alternatively, you may have one of the rare forms of celiac disease that does not respond to dietary changes.
Celiac disease tests may be negative if you have not consumed any gluten for several weeks to months prior to testing. If your health care practitioner still suspects celiac disease, the practitioner may do a gluten challenge – having you introduce gluten back into your diet for several weeks or months to see if your symptoms return. At that time, celiac disease tests may be repeated or a biopsy may be done to check for damage to the villi in the intestine.
Untreated, the long-term health effects have been associated with two times the risk of developing coronary heart disease and four times the risk of developing small intestine cancers. Diabetes, multiple sclerosis, infertility, miscarriage, and epilepsy have also been seen in some patients.
You may want to ask your doctor the following questions:
- What is gluten and what contains gluten?
- What is the difference between celiac disease and an allergy to wheat and other grains?
- Can I outgrow or desensitize myself to celiac disease?
- Do I need to follow a gluten-free diet if I have been diagnosed with celiac disease but have never had any symptoms?
- Should other members of my family be tested?