Advocacy - Test Utilization Guide

Anti-Gliadin Antibody Assay


Optimal Testing: ADLM's Guide to Lab Test Utilization

Anti-gliadin Antibody Assay: Optimal Testing Recommendations

  • Antibodies against native gliadin (AGA) are considered obsolete and not recommended for the diagnosis of celiac disease (CD).
  • Immunoglobulin A anti-tissue transglutaminase (TTG-IgA) antibody is the preferred single test for the serologic diagnosis of CD if patient is on a regular (gluten-containing diet.
  • Concurrent measurement of total IgA should be considered if the patient has not previously been tested for IgA deficiency.
  • Testing of CD should be considered in patients with signs or symptoms suggestive of CD, including diarrhea, weight loss, abdominal pain, or laboratory abnormalities such as unexplained serum aminotransferase levels. Testing of asymptomatic patients in populations at higher risk of CD may also be considered.
  • Symptomatic patients with a high pretest suspicion for CD should undergo duodenal biopsy irrespective of serologic results.
  • In adult patients with elevated TTG IgA level, confirmation of the diagnosis of CD with biopsy is recommended.
  • Non-biopsy criteria for the diagnosis of CD in children include high level TTG-A (>10X upper limit of reference range) and positive anti-endomysial antibody (EMA) results in a second sample.
  • In patients with IgA deficiency, IgG-based testing (TTG-IgG or DGP-IgG) should be performed.
  • Combining TTG-IgA with DCP-IgG when testing for CD in children younger than 2 who are not IgA deficiency no longer justified.
  • All diagnostic serologic testing should be done in patients on a gluten-containing diet.

Guidelines for Test Utilization

What does the test tell me?

AGA testing is considered obsolete and not recommended for the diagnosis of celiac disease (CD).

IgA deficient patients with positive TTG/DGP IgG results are recommended to undergo follow-up biopsy to confirm the diagnosis of CD. [back to top]

When should I order this test?

TTG-IgA has excellent diagnostic sensitivity and specificity in IgA sufficient patients. Anti-DGP has an important role in the diagnostic algorithm, especially in the IgG class in IgA-deficient patients, as detailed under the Recommendation Section. [back to top]

When should I NOT order this test?

Do not order the outdated AGA test. Using AGA results in lower diagnostic accuracy and unnecessary costs. [back to top]

How should I interpret the result?

AGA testing is no longer indicated. [back to top]

Is the test result diagnostic/confirmatory of the condition?

No, the AGA has been replaced by newer serologic tests (above).

If the suspicion of CD is high, intestinal biopsy should be pursued even if serologies are negative. Familial occurrence and genetic influence in the pathogenesis of CD has been recognized. HLA DQ2 and DQ8 genotyping is recommended if biopsy and serology results disagree or if patients are on a gluten-free diet. [back to top]

Are there factors that can affect the lab result?

IgA deficiency may result in false negative anti-TTG & anti-DGP tests if only the IgA class is measured. [back to top]

Are there considerations for special populations?

Classic AGA should not be used for pediatric patients.

Serological testing for CD in children <2 years of age has been discussed under the Recommendations Section. [back to top]

What other test(s) might be indicated?

Total IgA, TTG-IgA, TTG/DGP-IgG, and EMA, Intestinal biopsy, and HLA-DQ2/DQ8 genotyping might be indicated depending on the specific situation for the diagnosis of CD. [back to top]

References

Rubio-Tapia A, et al. American College of Gastroenterology Guidelines Update: Diagnosis and Management of Celiac Disease. Am J Gastroenterol. 2023; 118:59–76.

Elli L, et al. Guidelines for best practices in monitoring established coeliac

disease in adult patients. Nature Reviews Gastroenterol. & Hepatol. Published Online: 18 Dec, 2023

Shiha M, et al. Accuracy of the No-Biopsy Approach for the Diagnosis of Celiac Disease in Adults: A Systematic Review and Meta-Analysis. Gastroenterol. 7 Feb, 2024, in press


Last reviewed: December 2024. The content for Optimal Testing: the Association for Diagnostics & Laboratory Medicine’s (ADLM) Guide to Lab Test Utilization has been developed and approved by the the Academy of Diagnostics & Laboratory Medicine and ADLM’s Science and Practice Core Committee.

As the fields of laboratory medicine and diagnostic testing continue to grow at an incredible rate, the knowledge and expertise of clinical laboratory professionals is essential to ensure that patients received the highest quality and most useful laboratory tests. ADLM’s Academy and Science and Practice Core Committee have developed a test utilization resource focusing on commonly misused tests in hospitals and clinics. Improper test utilization can result in poor patient outcomes and waste in the healthcare system. This important resource geared toward medical professionals recommends better tests and diagnostic practices. Always consult your laboratory director to make sure these recommendations are appropriate for your patient population.

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