Anti-Tissue Transglutaminase Immunoglobulin A (tTG IgA)

tTg-IgA is a highly specific marker for diagnosing coeliac disease and monitoring its management.

📋 About This Biomarker

The Anti-Tissue Transglutaminase IgA (tTg-IgA) test is a key diagnostic tool for coeliac disease, an autoimmune condition triggered by gluten ingestion. This biomarker measures the level of antibodies your immune system produces in response to tissue transglutaminase, an enzyme found throughout your body but particularly in the small intestine. When someone with coeliac disease consumes gluten, their immune system mistakenly attacks this enzyme, leading to damage in the intestinal lining. This damage can interfere with nutrient absorption, causing symptoms like diarrhoea, fatigue, weight loss, and nutrient deficiencies. Testing for tTg-IgA is highly specific for coeliac disease and can also help monitor treatment efficacy once gluten has been removed from the diet. It offers a window into how well the body is managing its immune response and intestinal health, providing valuable insights for diagnosis and management.

🎯 Why We Test This

Testing for tTg-IgA helps diagnose coeliac disease, an autoimmune condition triggered by gluten. It’s also used to monitor the effectiveness of a gluten-free diet and ensure the intestinal lining is healing. It’s particularly important for individuals experiencing gastrointestinal symptoms, unexplained nutrient deficiencies, or conditions associated with coeliac disease, such as type 1 diabetes or thyroid disorders.

⚠️ What Affects It

Several factors can influence tTg-IgA levels. Consuming gluten is the primary trigger for increased levels in individuals with coeliac disease. Additionally, IgA deficiency - a condition where the body doesn’t produce enough Immunoglobulin A - can lead to falsely low or normal tTg-IgA levels, making it essential to test total IgA levels simultaneously. Other autoimmune conditions, such as type 1 diabetes or inflammatory bowel disease, may also have a mild impact on tTg-IgA levels. Testing accuracy depends on consuming enough gluten before the test (typically at least 10 grams daily for 6 weeks). Lastly, adherence to a gluten-free diet can lower or normalise tTg-IgA levels.

📈 How to Improve

For elevated or near-elevated levels, adopting a strict gluten-free diet is the most effective intervention. Identifying hidden sources of gluten in processed foods, sauces, and medications can help normalise levels. Regular follow-ups ensure adherence and healing. For levels within or near the lower range, no action is needed unless symptoms or other conditions (e.g., IgA deficiency) are present.

📊 Understanding Your Results (FLU)

Low
Undetectable levels are expected in individuals without coeliac disease or those with coeliac disease on a strictly gluten-free diet. However, if coeliac symptoms persist, IgA deficiency should be investigated, as this can cause false-negative results.
Optimal
Normal tTg-IgA levels generally indicate no significant immune response to gluten, suggesting the absence of coeliac disease. For individuals with coeliac disease who are on a gluten-free diet, normal levels signify effective dietary management and healing of the intestinal lining. Levels nearing the upper limit may suggest the early stages of coeliac disease or incomplete adherence to a gluten-free diet. This scenario often warrants further testing, such as a gluten challenge or biopsy, especially if symptoms are present. A careful review of dietary habits is essential to rule out unintentional gluten exposure. Low but detectable levels are not clinically significant in most cases. For individuals with coeliac disease on a strict gluten-free diet, it reflects adherence and effective management of the condition.
High
Elevated tTg-IgA levels strongly suggest coeliac disease. High levels indicate an active immune response where the body is attacking its intestinal lining due to gluten ingestion. This is a significant sign of autoimmune activity, and further investigation, including a biopsy of the small intestine, is often needed for a definitive diagnosis. Continued high levels after a confirmed diagnosis might indicate accidental gluten exposure or non-compliance with a gluten-free diet.
Also known as: Anti-Tissue transglutaminase IgA (tTg-IgA), TTG IgA, TTG IgA (human recombinant), Anti-Tissue Transglutaminase Immunoglobulin A, TTG-IgA