Interpretation of Negative Celiac Disease Serology
These negative serologic results effectively rule out celiac disease, and no further celiac-specific workup is needed. 1, 2
Understanding Your Test Results
Your serologic panel shows:
- Anti-gliadin IgG antibody: Low (5)
- Anti-gliadin IgA antibody: Not specified but implied negative
- Tissue transglutaminase IgA antibody: Negative (<2)
This combination of negative tissue transglutaminase IgA (tTG-IgA) and low anti-gliadin antibodies excludes active celiac disease with high confidence. 1, 2
Why These Results Rule Out Celiac Disease
tTG-IgA is the most reliable single test for celiac disease screening, with 90-96% sensitivity and >95% specificity in adults. 2 A negative result (<2) makes celiac disease highly unlikely. 1
Anti-gliadin antibodies (especially IgG) are not specific for celiac disease and are found in only 50% of non-celiac gluten sensitivity cases, as well as in 2-8% of healthy controls. 3 Low levels do not suggest celiac disease. 3
The combination of negative tTG-IgA with low anti-gliadin antibodies provides strong evidence against celiac disease, as 90-96% of untreated celiac patients would have elevated tTG-IgA. 2
Important Considerations Before Accepting These Results
Confirm Adequate Gluten Intake During Testing
- You must have been consuming at least 10g of gluten daily (approximately 3 slices of wheat bread) for 6-8 weeks before testing to ensure accurate results. 1, 2 If you had already reduced or eliminated gluten before testing, these results may be falsely negative. 1
Rule Out IgA Deficiency
- Total IgA levels should be measured to exclude selective IgA deficiency, which occurs in 1-3% of celiac patients and causes falsely negative IgA-based tests. 1, 2 If you are IgA-deficient, IgG-based tests (IgG deamidated gliadin peptide and IgG tissue transglutaminase) should be performed instead. 1, 4
When to Consider Further Testing Despite Negative Serology
Proceed to upper endoscopy with duodenal biopsies only if:
- Clinical suspicion remains extremely high (unexplained iron deficiency anemia, chronic diarrhea with weight loss, family history of celiac disease, associated autoimmune conditions like type 1 diabetes or autoimmune thyroid disease). 1, 2
- You were consuming adequate gluten when tested and total IgA levels are normal. 1, 2
HLA-DQ2/DQ8 genetic testing has >99% negative predictive value—absence of both alleles virtually excludes celiac disease—but should only be used in specific scenarios where celiac disease is strongly suspected despite negative serology. 1, 2
Alternative Diagnoses to Consider
If you have gastrointestinal symptoms despite negative celiac serology:
- Non-celiac gluten sensitivity may be present, though this cannot be diagnosed with serology and requires symptom response to gluten-free diet after celiac disease is excluded. 3
- Irritable bowel syndrome, small intestinal bacterial overgrowth, inflammatory bowel disease, or other functional gastrointestinal disorders should be considered. 2
Critical Pitfall to Avoid
Never start a gluten-free diet based on symptoms alone without confirmed celiac disease. 2 This can lead to nutritional deficiencies, unnecessary dietary restrictions, and makes future diagnostic testing unreliable if celiac disease needs to be reconsidered. 1, 2
Repeat Testing Indications
Repeat celiac serology only if: