From the Guidelines
Immunoglobulin A (IgA) tissue transglutaminase test is used to diagnose Coeliac disease.
Key Points
- The IgA tissue transglutaminase test is a serological test used to detect the presence of Coeliac disease, a chronic small intestinal immune-mediated enteropathy triggered by the ingestion of gluten 1.
- The test is highly sensitive and specific in both adults and children, with a sensitivity of >90% and specificity of typically slightly higher 2.
- The test is recommended as the initial detection of possible Coeliac disease, and positive results may warrant confirmation by duodenal biopsy 3.
- In patients with IgA deficiency, alternative tests such as IgG tissue transglutaminase and IgG or IgA deaminated gliadin peptides may be used 2.
- The IgA tissue transglutaminase test is considered a highly efficient strategy for determining the presence of Coeliac disease in patients presenting with chronic diarrhea 2.
Diagnosis of Coeliac Disease
- The diagnosis of Coeliac disease is typically made using a combination of serological tests, including IgA tissue transglutaminase, and endoscopic intestinal biopsy 1.
- The IgA tissue transglutaminase test is a key component of this diagnostic approach, and is often used as the initial test to detect the presence of Coeliac disease 4, 3.
From the Research
Immunoglobulin A (IgA) Tissue Transglutaminase Test
The Immunoglobulin A (IgA) tissue transglutaminase test is used to diagnose celiac disease.
- The test measures the level of IgA antibodies to tissue transglutaminase in the blood 5, 6, 7, 8, 9.
- Tissue transglutaminase is the main autoantigen recognized by endomysial antibodies, which are a hallmark of celiac disease 5.
- The test has high sensitivity and specificity for diagnosing celiac disease, with a sensitivity of 92% and a specificity of 98% 5, 8.
Diagnostic Accuracy
The diagnostic accuracy of the IgA tissue transglutaminase test has been confirmed in several studies:
- A study published in 1999 found that the test had a diagnostic sensitivity, specificity, and positive predictive value of 92%, 98%, and 98%, respectively 5.
- A study published in 2004 found that the test had a sensitivity of 92% and a positive predictive value of 0.77 for samples from primary care and 0.92 for samples from hospital sources 8.
- Another study published in 2004 found that the positive predictive value of IgA anti-tissue transglutaminase antibody for biopsy-confirmed celiac disease was 54%, but increased to 97% when combined with anti-endomysium antibody testing 9.
Clinical Utility
The IgA tissue transglutaminase test is recommended as a first-line serological test for celiac disease:
- The test is useful for screening for celiac disease in pediatric patients, with a sensitivity of 89% and a negative predictive value of 98% 7.
- The test is also useful for monitoring the response to treatment and for detecting relapse in patients with celiac disease 5, 8.
- However, false-positive results can occur, and clinical utility and diagnostic efficiency are improved when positive results are confirmed with anti-endomysium antibody testing 9.