Understanding Blood Tests for Coeliac Disease
Learn which blood tests can indicate coeliac disease and how to interpret their results.
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What is Coeliac Disease?
Coeliac disease is a chronic autoimmune disorder where the ingestion of gluten - a protein found in wheat, barley, and rye - triggers an immune response that damages the small intestine. This damage affects nutrient absorption, which can lead to symptoms such as diarrhea, bloating, fatigue, and malnutrition. Diagnosing coeliac disease often involves both blood tests and a biopsy of the small intestine.
Blood Tests for Coeliac Disease
Blood tests are the first step in diagnosing coeliac disease. They help identify specific antibodies produced by the immune system in response to gluten. Here are the most common tests used to screen for coeliac disease:
1. Tissue Transglutaminase Antibodies (tTG-IgA)
The tTG-IgA test is the most commonly used test for screening coeliac disease. It measures the level of antibodies against tissue transglutaminase, an enzyme found in the intestines. A high level of tTG-IgA antibodies suggests that the body is reacting to gluten, indicating the possibility of coeliac disease.
2. Endomysial Antibodies (EMA-IgA)
The EMA-IgA test measures the presence of antibodies against the endomysium, a connective tissue in the small intestine. This test is highly specific, meaning a positive result strongly indicates coeliac disease. However, it is less commonly used due to its higher cost and complexity.
3. Deamidated Gliadin Peptide (DGP-IgA and DGP-IgG)
The DGP test measures antibodies against deamidated gliadin peptides, which are components of gluten. This test can be particularly useful in children under two years old or when tTG-IgA or EMA-IgA tests are inconclusive, or if the patient has a known IgA deficiency.
How to Interpret Blood Test Results
Positive Results
A positive result on any of these tests suggests that further investigation is needed. However, it does not definitively diagnose coeliac disease. A biopsy of the small intestine is typically required to confirm the diagnosis.
Negative Results
A negative result usually means that coeliac disease is unlikely, especially if you have been consuming gluten regularly before the test. However, if symptoms persist, further evaluation may be necessary.
When to Consult a Doctor
If your blood tests suggest the possibility of coeliac disease, it's important to consult a healthcare provider. They may recommend further testing, such as a biopsy, to confirm the diagnosis. Additionally, if you experience symptoms of coeliac disease, such as chronic diarrhea, abdominal pain, bloating, unexplained weight loss, or fatigue, seeking medical advice is advisable.
Frequently Asked Questions
Can I have coeliac disease with normal blood test results?
Yes, in rare cases, you might have coeliac disease even if your blood tests are normal. This is why a biopsy is often used for a definitive diagnosis.
Do I need to eat gluten before taking a blood test for coeliac disease?
Yes, it is generally recommended to consume gluten regularly before the test to ensure accurate results. Avoiding gluten prior to testing can lead to false-negative results.
Can blood tests be used to monitor coeliac disease?
Yes, blood tests can be used to monitor adherence to a gluten-free diet and the effectiveness of treatment over time.
Conclusion
Understanding blood tests for coeliac disease can help you make informed decisions about your health. Always consult with a healthcare professional for personalized advice and treatment options. Remember, this information is not a substitute for professional medical advice.