Reference Interval:
| Test Number
| Components
| Reference Interval
| | 0097709 | Tissue Transglutaminase (tTG) Antibody, IgA
| 19 Units or less: Negative
20-30 Units: Weak Positive
31 Units or greater: Moderate to Strong Positive
| | 0050736 | Endomysial Antibody, IgA by IFA
| Less than 1:10
|
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| Interpretive Data: |
Tissue Transglutaminase Antibody, IgA: Presence of the tissue transglutaminase (tTG) IgA antibody is associated with gluten-sensitive enteropathies such as celiac disease and dermatitis herpetiformis. tTG IgA antibody concentrations greater than or equal to 100 Units usually correlate with results of duodenal biopsies consistent with a diagnosis of celiac disease. For antibody concentrations greater than 20 Units but less than 100 Units, additional testing for endomysial (EMA) IgA concentrations may improve the positive predictive value for disease.
Endomysial Antibody, IgA by IFA: The endomysial antigen has been identified as the protein cross-linking enzyme known as tissue transglutaminase.
|
| Note: |
Testing for tTG IgA antibodies is recommended as an initial screen to identify patients at risk for celiac disease, and in whom duodenal biopsy should be performed to confirm disease.
Some patients may have positive tTG IgA but negative EMA IgA and/or deamidated gliadin peptide (DGP) IgA results, which may be associated with false positivity or may indicate early disease. Close clinical correlation with continued testing may be indicated in patients with a family history of or who are at increased risk for celiac disease. A positive serology but normal biopsy may also indicate a gluten-free diet (GFD) prior to testing, latent disease, or early enteropathy. Re-challenge with a gluten diet may be recommended if GFD had been initiated prior to subsequent testing. In the case of latent or early disease, HLA DQ2 and DQ8 testing may be necessary to determine risk for disease.
For patients with a high degree of suspicion for celiac disease and who test negative for tTG, EMA, and/or DGP IgA tests, selective IgA-deficiency should be considered and testing for tTG, EMA, and/or DGP IgG antibodies performed.
If serology is negative and suspicion of celiac disease is strong, intestinal biopsy may be warranted. Biopsy is particularly important for patients with diarrhea, steatorrhea, weight loss, failure to thrive, or with inherited genetic deficiencies such as Down or Turner syndromes.
Specimen is screened using tissue transglutaminase IgA by ELISA. If tTG IgA is 20 units or greater, then EMA IgA by IFA testing will be added. Additional charges apply. All EMA IgA by IFA testing is titered to endpoint.
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| CPT Code(s): |
83516 tTG IgA; if reflexed, add 86256 EMA IgA by IFA
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Cross References: |
Anti-EMA (Tissue Transglutaminase (tTG) Antibody, IgA with Reflex to Endomysial Antibody, IgA by IFA, Anti-Endomysial (Tissue Transglutaminase (tTG) Antibody, IgA with Reflex to Endomysial Antibody, IgA, Antiendomysial (Tissue Transglutaminase (tTG) Antibody, IgA with Reflex to Endomysial Antibody, IgA, Celiac disease (Tissue Transglutaminase (tTG) Antibody, IgA with Reflex to Endomysial Antibody, IgA), Endomysial Antibody, IgA (Tissue Transglutaminase (tTG) Antibody, IgA with Reflex to Endomysial Anti, Gluten sensitivity (Tissue Transglutaminase (tTG) Antibody, IgA with Reflex to Endomysial Antibody, |
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