Laboratory Services

Tissue Transglutaminase (tTG) Antibody, IgA

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Updated Test Information:

Test Description
Tissue Transglutaminase (tTG) Antibody, IgA
Synonym(s)

tTG, Celiac

Test ID
TTGA
General Information

Tissue transglutaminase (tTG) has been identified as the major autoantigen in celiac disease. IgA antibodies against tTG are highly disease specific serological markers for celiac disease and dermatitis herpetiformis. Patients with selective IgA deficiency may yield false negative tTG IgA results. Assay results should be used in conjunction with clinical findings and other serological tests. Antibodies directed against gliadin, its deamidated products, and tTG are dependent on the ingestion of gluten. For this reason, serology testing is best performed in patients on a gluten-containing diet. In children younger than 2 years, it is recommended to combine tissue transglutaminase (tTG) testing with deamidated gliadin (DGP) IgA and IgG.

Specimen Type

Serum

Alternate Specimen Type

Plasma (EDTA or Citrate)

Specimen Requirements

Tiger

Additional Processing Details

Heparin interferes with the measurement of tTG antibodies.
Caution: Serum/plasma samples are not to be repeatedly frozen and thawed, since this can cause analyte deterioration. They are to be thawed only once.

Stability

Stored at 22˚C: 8 hrs
Stored at 2-8˚C: 1 week
If assays are not completed within 1 week or the specimen is to be stored beyond 1 week, the serum/plasma should be frozen at or below -20˚C.

Unacceptable Specimen Conditions

Li-Heparin, lipemic, hemolyzed or microbially contaminated samples.

Limitations

In children younger than 2 years, it is recommended to combine tissue transglutaminase (tTG) testing with deamidated gliadin (DGP) IgA and IgG.

Antibodies directed against gliadin, its deamidated products, and tTG are dependent on the ingestion of gluten. For this reason, serology testing is best performed in patients on a gluten-containing diet.

Methodology

Fluorescent enzyme immunoassay (FEIA)

Estimated TAT

2-5 days

Testing Schedule

Monday-Saturday, alternating days

CPT Code(s)

83516

Minimum Sample Volume

1 mL

Pediatric Min. Volume (if applicable)

500 uL

Reference Range

Negative < 7 U/mL
Equivocal 7-10 U/mL
Positive > 10 U/mL

Performing Lab

Incyte Diagnostics

LOINC Code(s)

46128-5