Primary Causes & Action Plans
tTG-IgA (Tissue Transglutaminase Antibody)
Primary screening test for celiac disease tTG-IgA is the most specific and sensitive screening test for celiac disease. Positive result requires confirmation with intestinal biopsy.
Target Negative (< 4 U/mL)
Suggested Action Plan
If positive, see gastroenterologist for endoscopy and intestinal biopsy. Start gluten-free diet only after biopsy confirmation (gluten-free diet invalidates biopsy).
Total IgA
Confirms adequate IgA level to validate tTG-IgA test If total IgA is deficient, tTG-IgA can be falsely negative. Total IgA is tested to validate the screening test.
Target > 70 mg/dL
Suggested Action Plan
If total IgA is low, alternative celiac testing (deamidated gliadin peptide-IgG) should be used. Retest total IgA; it may normalize after gluten elimination.
Endomysium Antibody (EMA)
Confirmatory test for celiac disease EMA is more specific than tTG-IgA. Positive tTG-IgA with positive EMA strongly suggests celiac disease.
Target Negative
Suggested Action Plan
If tTG-IgA is positive and EMA is negative, intestinal biopsy becomes even more important for diagnosis.
HLA-DQ2/DQ3 Genotyping
Genetic test: negative result excludes celiac disease Nearly all celiac patients carry HLA-DQ2 or DQ3. Negative genotype essentially excludes celiac disease (99% sensitivity).
Target Positive DQ2 or DQ3
Suggested Action Plan
If HLA genotype is negative and tTG-IgA is positive, celiac disease is very unlikely. Consider alternative diagnoses (non-celiac gluten sensitivity, IBS).