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Celiac Disease Reflexive Cascade, Serum
Ordering Recommendation
Preferred reflex test to evaluate for suspected celiac disease (CD) or dermatitis herpetiformis (DH). May be used to screen for CD or DH in individuals at increased risk. For additional information, including details on the reflex pattern for this test, refer to the Celiac Disease Reflexive Cascade, Serum Test Fact Sheet.
When testing for suspected DH, use in conjunction with Immunobullous Disease Antibody Panel (3001409) is recommended.
New York DOH Approval Status
Specimen Required
Serum separator tube (SST).
Separate serum from cells ASAP or within 2 hours of collection. Transfer 3 mL serum to an ARUP standard transport tube. (Min: 1.5 mL)
Refrigerated
Contaminated, grossly hemolyzed, grossly icteric, or grossly lipemic.
After separation from cells: Ambient: 48 hours; Refrigerated: 1 week; Frozen: 30 days
Methodology
Semi-Quantitative Particle-Based Multianalyte Technology (PMAT)
Performed
Sun-Sat
Reported
2-6 days
Reference Interval
| Test Number |
Components |
Reference Interval |
|---|---|---|
| Tissue Transglutaminase (tTG) Ab, IgA | 0.00 - 4.99 FLU |
Interpretive Data
Presence of the tissue transglutaminase (tTG) IgA antibody is associated with gluten-sensitive enteropathies such as celiac disease and dermatitis herpetiformis. Individuals with positive results should be confirmed with small intestinal biopsy to establish celiac disease diagnosis. tTG IgA antibody concentrations greater than 50 FLU exhibits higher correlation with results of duodenal biopsies consistent with celiac disease. For antibody concentrations greater than or equal to 5 FLU but less than 10 FLU, additional testing for endomysial (EMA) IgA concentrations may improve the positive predictive value for disease. A decrease in tTG IgA antibody concentration after initiation of a gluten-free diet may indicate a response to therapy.
FDA
Note
In individuals who produce sufficient IgA, the most sensitive and specific serologic test for celiac disease (CD) diagnosis is tissue transglutaminase (tTG) IgA. In individuals who are IgA deficient, tTG IgG and deamidated gliadin peptide (DGP) IgG antibody testing is recommended.
This reflexive panel test begins by assessing the presence of immunoglobulin A (IgA) using internal control beads. This assay does not measure IgA but flags samples when low or deficient IgA is detected. In the presence of low or deficient IgA (flags), tTG IgG and DGP IgG antibody testing will be added.
In samples with sufficient IgA (no flag), tTG IgA concentrations will be measured as an initial screen. If tTG IgA results are negative, then no further testing will be performed. If tTG IgA results are a weak or moderate positive (greater than 5 FLU but less than 10 FLU), additional testing for endomysial antibody (EMA) IgA and deamidated gliadin peptide (DGP) antibody IgA will be added and reported. If tTG IgA results are a strong positive (greater than 10 FLU), then no further testing will be performed.
If both tTG IgA and DGP IgA are below the limit of detection (tTG less than 1.02 FLU and DGP less than 0.72 FLU), then tTG IgG and DGP IgG antibody testing will be added, even in the absence of an IgA control flag, due to a suspected low-IgA state in the patient.
Refer to the Additional Technical Information document for more details.
All serologic tests used to diagnose CD should be performed while the patient is on a gluten-containing diet. Upon initiation of a gluten-free diet, antibody titers decline in treatment-responsive patients and the time frame to normalize titers varies by case. Close clinical correlation with continued testing may be indicated in patients who have a family history or increased risk for CD. If serology is negative and suspicion for CD remains strong, intestinal biopsy may still be warranted to establish a diagnosis.
In patients with dermatitis herpetiformis (DH), uneven antibody patterns are possible. Concurrent immunobullous disease panel testing and CD reflexive panel testing are recommended to assess for DH.
Hotline History
Hotline History
CPT Codes
86364; if reflexed additional CPT codes may apply: 86364, 86231; 86258 x2
Components
| Component Test Code* | Component Chart Name | LOINC |
|---|---|---|
| 0097709 | Tissue Transglutaminase (tTG) Ab, IgA | 46128-5 |
