What is the name of the serum test for celiac disease, specifically the (tissue transglutaminase antibody) test?

The Primary Serum Test for Celiac Disease

The primary serum test for celiac disease is the tissue transglutaminase IgA antibody (tTG-IgA) test. 1

Diagnostic Testing Algorithm for Celiac Disease

First-Line Testing

• tTG-IgA antibody test is the preferred initial serological test for individuals over 2 years of age due to its:
  • High sensitivity (90-96%)
  • High specificity (>95%)
  • Convenience of automated ELISA testing 1, 2
• Total serum IgA level should be measured simultaneously to rule out IgA deficiency 1, 2

Special Populations

• For children under 2 years: Combine tTG-IgA with IgG and IgA deamidated gliadin peptide antibodies 2
• For IgA-deficient patients: Use IgG-based testing including:
  • IgG tTG
  • IgG deamidated gliadin peptide (DGP)
  • IgG endomysial antibodies (EMA) 1, 2

Confirmatory Testing

• Endomysial antibody (EMA-IgA) test is recommended as a second-line confirmatory test when:
  • tTG-IgA results are weakly positive
  • Additional confirmation is needed 1
• EMA testing has slightly lower sensitivity but higher specificity than tTG-IgA 1, 3

Critical Testing Considerations

Testing Requirements

• Patient must be on a gluten-containing diet for at least 6 weeks prior to testing 1, 2
• False negatives occur if testing is performed after starting a gluten-free diet 2

Interpreting Results

• High tTG-IgA levels (>10× upper limit of normal):
  • Highly predictive of celiac disease
  • When combined with positive EMA, has nearly 100% positive predictive value 1
• Borderline or weakly positive results should be followed with EMA testing 1

Diagnostic Confirmation

• Small intestinal biopsy remains the gold standard for diagnosis in adults 1, 2
• Multiple duodenal biopsies should be obtained during endoscopy 1, 2

Common Pitfalls to Avoid

1. Failing to check total IgA levels - IgA deficiency occurs in 1-3% of celiac patients and leads to false-negative tTG-IgA results 1

2. Testing after gluten restriction - Antibody levels decrease rapidly on a gluten-free diet, reducing test sensitivity 1, 4

3. Relying on at-home celiac tests - These have lower accuracy than laboratory-based tests and lack professional oversight 2

4. Using antibody tests alone to monitor treatment response - tTG-IgA and EMA-IgA have low sensitivity (<50%) for detecting persistent villous atrophy in patients on gluten-free diets 4

5. Using antigliadin antibodies as primary screening - These older tests have inferior accuracy compared to tTG-IgA and EMA-IgA 1

The development of the tTG-IgA test represented a significant advancement in celiac disease diagnosis, providing a highly accurate, automated alternative to the more labor-intensive EMA test, while targeting the same autoantigen 1, 5, 6.