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Beaumont Laboratory

Tissue Transglutaminase (IgA)

TTGA, TTG IgA, Tissue Transglutaminase Antibody, IgA, EPIC: LAB6912, SOFT: TTGAB

Specimen Collection Criteria

Collect: One Gold-top SST tube.

Physician Office/Drawsite Specimen Preparation

Let specimen clot 30-60 minutes then immediately centrifuge to separate serum from cells. Refrigerate (2-8°C or 36-46°F) the centrifuged collection tube within two hours of collection. (Min: 0.5 mL)

Preparation for Courier Transport

Transport: Centrifuged collection tube, refrigerated (2-8 °C or 36-46 °F). (Min: 0.5 mL)

Rejection Criteria

  • Plasma specimens.
  • Severely lipemic, contaminated, or hemolyzed specimens.


Specimen Stability for Testing:

Centrifuged SST Tubes and Microtainers® with Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 8  hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): Unacceptable

Red-top Tubes and Microtainers® without Separator Gels
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): Unacceptable
Frozen (-20°C/-4°F or below): Unacceptable

Serum Specimens (Pour-Overs)
Room Temperature (20-26°C or 68-78.8°F): 2 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 3 months

Specimen Storage in Department Prior to Disposal:

Refrigerated (2-8°C or 36-46°F): 7 days


Royal Oak Special Testing Laboratory.


Tuesday, Wednesday, Friday.
Results available in 2 business days.

Reference Range

Negative: Less than 20 units.
Weak Positive: 20 - 30 units.
Moderate-Strong Positive: Greater than 30 units.

Test Methodology

Enzyme-Linked Immunosorbent Assay.


Tissue transglutaminase antibodies appear to be highly specific for celiac disease and are useful to screen high-risk populations (e.g. first degree relatives of celiac patients, insulin dependent diabetics, etc) for celiac disease. However, histologic confirmation is required for diagnosis. Patients should not begin a gluten-free diet until after intestinal biopsy has been performed and the diagnosis is established. Serial tissue transglutaminase antibody testing may at times be useful to monitor dietary compliance.

Note: The endomysial antigen has been identified as the protein cross-linking enzyme known as tissue transglutaminase. Detection of tissue transglutaminase antibodies is an aid in the diagnosis of certain gluten-sensitive enteropathies, such as celiac disease and dermatititis herpetiformis. Human tTg IgA antigen is used in this assay.

Clinical Utility

Tissue transglutaminase is an enzyme that is normally located within endomysial cells. IgA autoantibodies to tissue transglutaminase have been shown to be highly correlated with active celiac disease.

Note: Patients with IgA deficiency may have falsely negative test results. If there is a high degree of suspicion for celiac disease, tissue transglutaminase antibodies (IgG) and an IgA level should be requested.

CPT Code


Test Codes


Last Updated


Microtainer® and Vacutainer® are registered trademarks of Becton, Dickinson and Company.
UroVysion® is a registered trademark of Abbott Laboratories. ThinPrep® is a registered trademark of Hologic, Incorporated.

This directory currently reflects information only for specimens collected and/or processed at the Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.