Doctors mainly test for celiac disease using blood tests and small intestine biopsies.
Testing for celiac disease aims to identify certain celiac-linked antibodies. These are proteins the immune system produces to attack certain tissues in response to perceived threats.
Doctors also check for celiac disease by examining gut tissue to check for damage.
Read on to learn more about tests for celiac disease. This article also discusses when doctors recommend them, whether it is possible to test for the condition at home, and more.
The main test for celiac disease is the tissue transglutaminase immunoglobulin A (tTG-IgA) test.
This blood test
According to the Celiac Disease Foundation, the tTG-IgA test is positive in around 93% of those with celiac disease and negative in roughly 96% of those without it.
Other blood tests include:
- IgA endomysial antibody (EMA): This test for another antibody relating to celiac gut damage is more expensive than the tTG-IgA test but more specific to celiac disease.
- Total serum IgA: This checks for IgA deficiency, a condition in 2% to 3% of those with celiac disease that may lead to a false negative result in tTG-IgA or EMA tests.
- Deamidated gliadin peptide (DGP IgA and IgG) tests: Doctors may carry out these tests if a person tests positive for IgA deficiency.
Doctors may request an IgG test for people with IgA deficiency. Different labs and clinics provide different tests, and
Once a blood test suggests the possible presence of celiac disease, a doctor will usually request a biopsy to confirm the diagnosis.
A biopsy involves collecting a tissue sample and checking it under a microscope for damage or cellular change.
A gastroenterologist, a specialist in treating gastrointestinal (GI) disorders, will perform an upper GI endoscopy. Before the procedure, they administer a local anesthetic to reduce sensation in the throat and possibly a sedative to induce relaxation.
They will then insert a long, flexible tube with an attached light and camera into the top part of the GI system through the mouth.
The gastroenterologist then passes a small tool through the tube to collect the tissue sample. Following this, they send the sample to a lab.
Around 1 in 4 people with celiac disease have a skin condition called dermatitis herpetiformis (DH). It usually leads to itchy, easy-to-burst blisters that develop on the knees, elbows, and buttocks.
Despite not being a direct celiac disease symptom, DH has close enough links to celiac disease. Doctors may test for it using a biopsy.
A dermatologist will usually administer a punch biopsy while the individual is under local anesthetic. A punch biopsy uses a tool resembling a cookie cutter to remove a sample of skin roughly 4 millimeters deep next to the lesion.
The dermatologist then sends this to a lab for testing, where they look for IgA deposits that appear in a certain pattern.
Testing for an absence of certain gene changes may help doctors
Those with celiac disease have changes or mutations in one of two genes: HLA-DQ2.5 and HLA-DQ8.
Around 3 in 10 people have these changes, and 3 in 100 of those with the changes develop celiac disease.
Learn more about celiac disease and genetics.
Doctors may recommend celiac disease tests if a person experiences symptoms of the condition. Celiac disease can cause symptoms such as:
- consistent digestive problems, including:
- fatigue
- unexplained weight loss
- consistent or severe mouth ulcers
People need to consult a doctor if they notice any of these symptoms.
Both genetic testing and antibody testing are available for home use.
While home testing can be accurate, a gut biopsy from a clinician is necessary for confirming a celiac disease diagnosis. At-home tests can provide more information but cannot replace clinic testing.
Some home tests can also check for gluten in the urine and stool. This can help check whether a person has had any gluten in their diet.
Learn more about at-home celiac disease tests.
People undergoing celiac disease blood tests need to continue to eat gluten until testing so that doctors can make an accurate diagnosis.
If a doctor is testing the body’s response to gluten in those who already have a celiac diagnosis, they may suggest a “gluten challenge.” This involves increasing daily gluten intake before a blood test, allowing antibodies to build in the bloodstream ahead of testing.
Recommendations differ on how much gluten to eat and for how long. A person’s doctor can advise on how much gluten they need to eat and how soon before the test to begin consuming gluten.
An individual needs to follow a gluten-free diet for the rest of their lives after receiving a celiac disease diagnosis.
Doctors may also carry out further testing to assess the effects of celiac disease, including blood tests to confirm levels of vitamins and minerals, especially iron. This is due to celiac disease’s effects on nutrient absorption.
For the same reason, doctors may need to test bone density using a DEXA scan, as low nutrient absorption can affect bone strength and make them more prone to fractures.
Below are answers to common questions about celiac disease.
What are three symptoms of celiac disease?
Celiac disease can cause over 200 symptoms, according to the Celiac Disease Foundation, and different people experience the disorder differently. However, GI symptoms, fatigue, and iron deficiency anemia are three major signs and symptoms of celiac disease.
What can people mistake for celiac disease?
Wheat allergy and non-celiac gluten sensitivity symptoms may overlap with those of celiac disease. Testing can help distinguish the conditions.
What is the tTG-IgA test for celiac disease?
The tTG-IgA test for celiac disease measures the number of antibodies in the blood that develop in response to gluten. It is the primary test for celiac disease, though a biopsy is the only way to confirm the diagnosis.
Doctors confirm celiac disease diagnoses primarily through blood tests and a gut biopsy. They may also need to request a skin biopsy to check for dermatitis herpetiformis.
Genetic testing can support the diagnosis if blood tests have not confirmed the presence of celiac disease-related antibodies.
People may need to continue eating gluten up until testing. Afterward, doctors may test for nutritional deficiencies, and a person will need to stick to a gluten-free diet to manage symptoms.