UW Hospital and Clinics Lab Test Directory
| Test Name: |
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Tissue Transglutaminase Ab, IgA
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| Test Code(s): |
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TTGIGA / XTTGA
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| CPT Code(s): |
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83516
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| Methodology: |
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ELISA
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| Clinical Significance: |
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Tissue Transglutaminase antibody assays are now considered the most sensitive and specific serologic tests for celiac disease. Although classically considered a gastrointestinal disorder, celiac disease can actually present with a variety of intestinal and extra-intestinal symptoms. It is an immune-mediated disorder triggered by exposure to specific dietary proteins (glutens) in wheat, barley, and rye. Affected individuals will show inflammation and atrophy of the small intestine on biopsy; this is the gold standard for diagnosis. Treatment is a gluten-free diet for life.
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| Days Performed: |
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Mon-Fri, dayshift - day varies.
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| Turnaround Time: |
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Stat: Not available stat.
Routine: 2 - 3 working days.
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Specimen Requirements
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| Specimen: |
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Blood
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| Collection Container: |
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Preferred: Red top
Also Acceptable:
Red cap with yellow ring (SST)
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| Collection Volume: |
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Preferred: 3 mL
Pediatrics: 1 mL
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| Sample Analyzed: |
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Serum
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| Volume Required: |
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Preferred: 1 mL
Pediatrics: 0.3 mL
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| Specimen Processing: |
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Centrifuge. Transfer cell-free serum to clear plastic vial. Refrigerate.
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| Specimen Transport: |
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Transport specimen to laboratory. Transport with coolant pack if coming from satellite or outreach location.
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| Unacceptable Criteria: |
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Grossly hemolyzed or grossly lipemic samples
Plasma and other body fluids
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| Stability: |
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Ambient: 2 days
Refrigerated: 14 days at 2-8°C
Frozen: 3 months at -20°C or lower
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Interpretation
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Reference Interval:
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6 years and up:
| Negative |
<20 units |
| Borderline |
20-30 units |
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Moderate to Strong
Positive
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>30 units |
Assay peformance not established for pediatric population under age 6
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| Test Limitations: |
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This test has high sensitivity and specificity for biopsy proven celiac disease. A small portion of the population is IgA deficient and will have a negative IgA TTg antibody test. If the patient has a high clinical suspicion of celiac disease and the IgA TTg antibody test is negative, quantitative serum IgA levels should be measured. If the patient is IgA deficient, IgG TTg antibody testing is recommended. The Immunology Laboratory will review IgG TTg antibody requests prior to sending them out.
Individuals on a gluten-free diet may have a negative IgA TTg result.
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tTG,Transglutaminase(tTG),Tissue Transglutaminase Ab IgA,Tissue Transglutaminase (tTG),Celiac Disease
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