Celiac disease is an autoimmune disorder where consuming gluten, a protein found in wheat, barley, and rye, damages the small intestine. This damage can hinder nutrient absorption, leading to various health problems. A comprehensive blood panel helps identify individuals who may have celiac disease. Understanding these tests and their results is essential for those undergoing testing.
Understanding the Comprehensive Panel
A comprehensive celiac disease panel typically includes several blood tests measuring antibodies produced by the immune system in response to gluten exposure. These tests are:
Tissue Transglutaminase IgA (tTG-IgA)
Endomysial Antibody IgA (EMA-IgA)
Deamidated Gliadin Peptide IgA and IgG (DGP-IgA/IgG)
Total Serum IgA
The tTG-IgA test identifies antibodies against tissue transglutaminase, an enzyme in the small intestine. The EMA-IgA test detects antibodies targeting the endomysium, a connective tissue layer. The DGP-IgA and DGP-IgG tests look for antibodies against deamidated gliadin peptides, which are gluten fragments. The Total Serum IgA test measures overall IgA antibody levels, serving as a control for potential IgA deficiency.
Interpreting Antibody Test Results
Interpreting antibody test results involves understanding what elevated, normal, or indeterminate levels suggest. Elevated tTG-IgA levels are often the primary indicator for celiac disease in adults and children. A significantly high tTG-IgA level suggests celiac disease.
The EMA-IgA test is highly specific for celiac disease; a positive result strongly indicates the condition. However, EMA-IgA is less sensitive than tTG-IgA, meaning some individuals with celiac disease might not have a positive EMA test.
DGP-IgA and DGP-IgG tests are useful in specific situations, such as in young children or when IgA-based tests might be unreliable. Elevated DGP-IgA/IgG levels can also indicate celiac disease, especially if other tests are inconclusive.
Normal or negative results suggest celiac disease is less likely, but they do not entirely rule it out. Individuals must consume gluten-containing foods for several weeks before blood tests, as avoiding gluten can lead to inaccurate or false-negative results.
Indeterminate or borderline results mean antibody levels are neither clearly positive nor negative. In such cases, further investigation is typically needed to clarify the diagnosis.
The Total Serum IgA test is important because an IgA deficiency can cause false-negative results in IgA-based antibody tests like tTG-IgA and EMA-IgA. If Total Serum IgA levels are low, healthcare providers often rely more on IgG-based tests, such as DGP-IgG or tTG-IgG, to screen for celiac disease. This helps ensure a potential IgA deficiency does not mask active celiac disease.
Deciphering Genetic Test Results
Genetic testing for celiac disease focuses on the presence or absence of specific human leukocyte antigen (HLA) genes, primarily HLA-DQ2 and HLA-DQ8. These genes are associated with celiac disease susceptibility, with most individuals with celiac disease possessing HLA-DQ2 or HLA-DQ8.
A positive genetic test result, indicating the presence of HLA-DQ2 or HLA-DQ8, means an individual has a genetic predisposition. However, having these genes is necessary but not sufficient for developing the condition; many people with these genes never develop celiac disease. For example, 30-40% of the general population carries at least one of these genes.
Conversely, a negative genetic test result, meaning the absence of both HLA-DQ2 and HLA-DQ8, makes celiac disease extremely unlikely. This result can effectively rule out celiac disease, particularly when the diagnosis is uncertain or an individual has already adopted a gluten-free diet before antibody testing. Genetic tests indicate a predisposition rather than active disease, distinguishing them from antibody tests that reflect an ongoing immune response.
What Happens After Your Results?
Once blood panel results are available, consult a healthcare professional. Only a doctor can interpret these results within the context of an individual’s symptoms, medical history, and overall health.
A positive blood test for celiac disease antibodies often leads to a recommendation for an upper endoscopy with a small intestinal biopsy. This procedure allows for direct visualization and tissue sampling of the small intestine to confirm damage characteristic of celiac disease. It is important to continue consuming gluten until all diagnostic tests, including the biopsy, are completed to ensure accurate results.
If blood tests are negative or indeterminate, but symptoms persist or there is a strong family history, further investigation may be warranted. A gastroenterologist might recommend additional tests or a re-evaluation of symptoms.
Receiving a celiac disease diagnosis means adopting a lifelong gluten-free diet, the primary treatment to manage the condition and promote intestinal healing. Regular follow-up with a healthcare team, including a physician and a registered dietitian, helps monitor progress, address nutritional deficiencies, and ensure adherence to the gluten-free diet.