Commonly Used Diagnostic Tests for Celiac Disease



Tissue transglutaminase (tTG) IgA antibodies

 - Most reliable noninvasive test and first-level screening test

 - High sensitivity and specificity

 - Falsely negative with IgA deficiency (3% of patients with celiac disease)

 - May be negative if on low-gluten diet

Tissue transglutaminase (tTG) IgG antibodies

 - Useful in patients with IgA deficiency

 - Widely variable sensitivity and specificity

IgA antiendomysial antibodies

 - May be useful in patients with borderline results for tTG antibodies

 - Sensitivity for celiac disease less than IgA anti-transglutaminase antibody test

IgG deamidated gliadin peptide antibodies

 - Useful in patients with IgA deficiency and in young children

 - Not as sensitive or specific as tTG IgA antibodies

HLA-DQ2 or HLA-DQ8

 - High negative predictive value for celiac disease

 - Test is complex and expensive

Small bowel biopsy

 - Reliable test, considered gold standard

 - Reflects response to treatment

 - Requires endoscopy and biopsy

 - Very expensive



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