Anti Tissue Transglutaminase IgA (Anti-TTG IgA)

Function

The Anti-Tissue Transglutaminase (tTG) IgA test is the primary screening blood test for Celiac Disease. Tissue Transglutaminase is an enzyme involved in the repair of cells. In individuals with Celiac Disease, the ingestion of gluten (a protein found in wheat, barley, and rye) triggers an autoimmune response where the body produces IgA antibodies against this enzyme, leading to inflammation and destruction of the small intestinal lining (villi).

Why it is Ordered

This test is ordered for patients exhibiting symptoms of malabsorption, such as chronic diarrhea, abdominal bloating, weight loss, or unexplained iron-deficiency anemia. It is also used to screen high-risk individuals, such as those with Type 1 Diabetes, Down Syndrome, or a first-degree relative with Celiac Disease. In pediatric patients, it is often used to investigate 'failure to thrive.'

Associated Conditions

• Celiac Disease: Gluten-sensitive enteropathy.
• Dermatitis Herpetiformis: A skin manifestation of gluten sensitivity.
• Malabsorption Syndromes: Leading to Vitamin D, B12, or Iron deficiencies.
• IgA Deficiency: About 2-3% of people with Celiac disease also have a selective IgA deficiency, which can cause a false negative on this specific test.

Clinical Management

A positive tTG-IgA result is usually followed by a small bowel biopsy to confirm the diagnosis (showing villous atrophy). Once diagnosed, the test is used periodically to monitor compliance with a gluten-free diet; antibody levels should drop significantly when gluten is removed from the diet.