Left undiagnosed, it can lead to serious health complications, including nutrient deficiencies, osteoporosis, infertility, and increased risk of intestinal cancers.
Diagnosing celiac disease can be complex because symptoms often overlap with other gastrointestinal disorders like irritable bowel syndrome (IBS) or lactose intolerance. That’s why healthcare providers rely on a combination of blood tests, genetic tests, and intestinal biopsies to confirm a diagnosis.
In this blog, we explore the various diagnostic tests for celiac disease, their purpose, and how they help in reaching an accurate diagnosis.
When Should You Get Tested for Celiac Disease?
Celiac disease can present with a wide range of symptoms, which may include:
1. Chronic diarrhea or constipation
2. Bloating and abdominal pain
3. Weight loss
4. Fatigue
5. Anemia (iron deficiency)
6. Skin rash (dermatitis herpetiformis)
7. Delayed growth or puberty in children
8. Infertility or miscarriages
If you or a family member exhibit these symptoms—or have a related autoimmune condition—your doctor may recommend tests for celiac disease.
1. Serologic (Blood) Tests
Blood tests are usually the first step in screening for celiac disease. They detect antibodies produced by the immune system in response to gluten ingestion.
a. Tissue Transglutaminase Antibodies (tTG-IgA)
1. Most commonly used screening test for celiac disease
2. Measures IgA antibodies against tissue transglutaminase, an enzyme targeted in celiac disease
3. Highly sensitive and specific
4. Patients must be on a gluten-containing diet for accurate results
b. Deamidated Gliadin Peptide (DGP) Antibodies
1. Useful when tTG results are negative but suspicion remains high
2. Can be helpful in testing young children under 2 years, where tTG may not be reliable
c. Total Serum IgA
1. Measures overall levels of IgA in the blood
2. Important because some people with celiac disease have IgA deficiency, which can give false-negative results in tTG-IgA testing
d. Endomysial Antibodies (EMA)
1. Highly specific for celiac disease but more expensive and less commonly used
2. Typically performed in specialized labs
2. Genetic Testing (HLA-DQ2 and HLA-DQ8)
1. Genetic tests help rule out celiac disease rather than confirm it.
2. Over 95% of people with celiac disease carry the HLA-DQ2 or HLA-DQ8 gene.
3. If you do not have either of these genes, celiac disease is extremely unlikely.
4. Particularly useful in patients who have already adopted a gluten-free diet and cannot undergo traditional blood or biopsy tests.
5. However, having the gene does not mean you will definitely develop celiac disease—it only means you're at increased risk.
3. Intestinal Biopsy
The gold standard for diagnosing celiac disease is a biopsy of the small intestine.
Procedure:
1. Done via upper endoscopy
2. A thin tube with a camera (endoscope) is passed through the mouth to the small intestine
3. Small tissue samples are collected for analysis
What It Detects:
1. Damage to the villi—tiny, finger-like projections in the small intestine.
2. In celiac disease, these villi become flattened, impairing nutrient absorption.
3. Biopsy is most commonly used to confirm the diagnosis after positive blood tests.
4. Skin Biopsy (For Dermatitis Herpetiformis)
Some people with celiac disease develop a chronic, itchy, blistering skin condition called dermatitis herpetiformis. In such cases:
1. A skin biopsy near the rash can reveal IgA deposits under the skin.
2. If positive, this can be considered diagnostic for celiac disease.
3. An intestinal biopsy may still be recommended to assess gut involvement.
5. Gluten Challenge (If Already Gluten-Free)
Many people try a gluten-free diet before getting formally tested, which can lead to false-negative results.
1. In such cases, a doctor may recommend a gluten challenge, which involves:
2. Eating gluten-containing foods (usually 3–10 grams per day, or about 2 slices of bread)
3. Continuing this for 6–8 weeks under medical supervision
4. Retesting with blood tests or biopsy after gluten exposure
Note: This process can cause uncomfortable symptoms and should only be done under a doctor’s guidance.
Do At-Home Celiac Tests Work?
Some companies offer at-home finger-prick tests that screen for tTG or DGP antibodies. While these can be a useful first step, they are not a substitute for formal diagnosis and should always be followed up with a physician.
Why Accurate Diagnosis Matters?
Misdiagnosing celiac disease can lead to:
1. Unnecessary dietary restrictions
2. Delayed treatment of other conditions
3. Continued intestinal damage in undiagnosed individuals
4. An accurate diagnosis ensures proper management and long-term health monitoring.
Summary
Celiac disease diagnosis requires a stepwise approach that begins with blood tests and may be followed by genetic testing or biopsy. The most accurate diagnosis is made while the individual is still consuming gluten, as avoiding gluten can interfere with test results.
If you suspect celiac disease—either due to symptoms or family history—speak to your healthcare provider. Early detection is key to preventing complications and ensuring a healthier future.
