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Test Code LABTTGAG Tissue Transglutaminase (tTG) IgA and IgG Antibodies, Serum

Additional Codes

Test Name in EPIC EPIC Test Code Mnemonic
TISSUE TRANSGLUT, IGA/IGG ABY LABTTGAG TTGAG

 

Useful For/Utility

Evaluating patients suspected of having celiac disease, including patients with compatible clinical symptoms, patients with atypical symptoms, and individuals at increased risk (family history, previous diagnosis with associated disease, positivity for HLA DQ2 and/or DQ8)

 

Monitoring adherence to gluten-free diet in patients with dermatitis herpetiformis and celiac disease

Methodology

Enzyme Immunoassay (EIA)

Clinical Information

Celiac disease (gluten-sensitive enteropathy, celiac sprue) results from an immune-mediated inflammatory process following ingestion of wheat, rye, or barley proteins that occurs in genetically susceptible individuals. The inflammation in celiac disease occurs primarily in the mucosa of the small intestine, which leads to villous atrophy. Common clinical manifestations related to gastrointestinal inflammation include abdominal pain, malabsorption, diarrhea, and constipation. Clinical symptoms of celiac disease are not restricted to the gastrointestinal tract. Other common manifestations of celiac disease include failure to grow (delayed puberty and short stature), iron deficiency, recurrent fetal loss, osteoporosis, chronic fatigue, recurrent aphthous stomatitis (canker sores), dental enamel hypoplasia, and dermatitis herpetiformis. Patients with celiac disease may also present with neuropsychiatric manifestations including ataxia and peripheral neuropathy, and are at increased risk for development of non-Hodgkin lymphoma. The disease is also associated with other clinical disorders including thyroiditis, type I diabetes mellitus, Down syndrome, and IgA deficiency.

 

Celiac disease tends to occur in families; individuals with family members who have celiac disease are at increased risk of developing the disease. Genetic susceptibility is related to specific HLA markers. More than 97% of individuals with celiac disease in the United States have DQ2 and/or DQ8 HLA markers, compared to approximately 40% of the general population.

 

A definitive diagnosis of celiac disease requires a jejunal biopsy demonstrating villous atrophy. Given the invasive nature and cost of the biopsy, serologic and genetic laboratory tests may be used to identify individuals with a high probability of having celiac disease. Subsequently, those individuals with positive laboratory results should be referred for small intestinal biopsy, thereby decreasing the number of unnecessary invasive procedures (see Celiac Disease Diagnostic Testing Algorithm in Special Instructions. In terms of serology, celiac disease is associated with a variety of autoantibodies, including endomysial, tissue transglutaminase (tTG), and deamidated gliadin antibodies. Although the IgA isotype of these antibodies usually predominates in celiac disease, individuals may also produce IgG isotypes, particularly if the individual is IgA deficient. The most sensitive and specific serologic tests are tTG and deamidated gliadin antibodies.

 

The treatment for celiac disease is maintenance of a gluten-free diet. In most patients who adhere to this diet, levels of associated autoantibodies decline and villous atrophy improves. This is typically accompanied by an improvement in clinical symptoms.

Specimen Requirements

Specimen Type: Serum

Container/Tube: Serum gel

Specimen Volume: 1 mL

Specimen Minimum Volume: 0.50 mL

Collection Instructions: UNACCEPTABLE: Markedly hemolyzed or lipemic specimens.

Specimen Transport Temperature

Refrigerate 5 days/Ambient NO

Day(s) Test Set Up

Monday through Friday (day shift only)

Performing Laboratory

Chemistry-

SMDC Clinical Lab

LOINC Code Information

Test ID Test Order Name Order LOINC Value
LABTTGAG Tissue Transglutaminase (tTG) IgA and IgG Antibodies 35681-6

 

Result ID Test Result Name Result LOINC Value
1230000274 Tissue Transglutaminase (tTG) IgA Antibody 46128-5
1230000273 Tissue Transglutaminase (tTG) IgG Antibody 56537-4

Reference Values

Tissue Transglutaminase Antibodies, IgA

<4.0 U/mL (negative)

4.0-10.0 U/mL (weak positive)

>10.0 U/mL (positive)

 

Tissue Transglutaminase Antibodies,IgG

<6.0 U/mL (negative)

6.0-9.0 U/mL (weak positive)

>9.0 U/mL (positive)

CPT Code Information

86364x2 - Tissue Transglutaminase, each immunglobulin class