Tissue Transglutaminase Antibody Test
Introduction to tTG Testing
Tissue Transglutaminase (tTG) antibody testing is the primary serological test for celiac disease diagnosis in pediatric populations. It offers high sensitivity and specificity for detecting celiac disease autoimmunity.
Key Points:
- Gold standard for celiac disease screening
- High sensitivity (>95%) and specificity (>95%)
- Essential first-line diagnostic tool
- Both IgA and IgG testing available
- Quantitative results guide management
Test Significance:
- Non-invasive diagnostic tool
- Monitoring disease activity
- Screening high-risk populations
- Treatment response assessment
- Research applications
Test Types and Methods
tTG-IgA Testing:
- Primary screening test
- Most sensitive marker
- First-line testing choice
- Requires normal IgA levels
- Age-dependent sensitivity
- Test Specifications
- Sample type: Serum
- Processing time: 24-48 hours
- Storage: 2-8°C
- Stability: 7 days
tTG-IgG Testing:
- Secondary screening test
- Used in IgA deficiency
- Complementary testing
- Lower sensitivity than IgA
- Important backup test
- Test Specifications
- Sample type: Serum
- Processing time: 24-48 hours
- Storage conditions same as IgA
- Different reference ranges
Testing Methods:
- ELISA
- Most common method
- Quantitative results
- Automated processing
- Standardized reporting
- Chemiluminescence
- High sensitivity
- Rapid turnaround
- Good reproducibility
- Modern platforms
Clinical Applications
Primary Indications:
- Diagnostic Screening
- Suspected celiac disease
- High-risk populations
- Family screening
- Associated conditions
- Monitoring
- Treatment response
- Dietary compliance
- Disease activity
- Research protocols
High-Risk Groups:
- First-degree relatives
- Type 1 diabetes patients
- Autoimmune thyroid disease
- Down syndrome
- Turner syndrome
- Chronic diarrhea/malabsorption
- Unexplained growth failure
Testing Procedure
Pre-analytical Factors:
- Patient Preparation
- No fasting required
- Continue gluten intake
- Document diet status
- Note medications
- Sample Collection
- Venous blood draw
- Appropriate tubes
- Proper labeling
- Transport conditions
Quality Control:
- Internal controls
- Calibration curves
- Reference standards
- Result validation
- Documentation
Result Interpretation
tTG-IgA Interpretation:
- Negative: <20 U/mL
- Borderline: 20-30 U/mL
- Positive: >30 U/mL
- Strong positive: >100 U/mL
tTG-IgG Interpretation:
- Negative: <6 U/mL
- Borderline: 6-10 U/mL
- Positive: >10 U/mL
Clinical Correlation:
- Result Categories
- Seronegative: Normal
- Potential: Borderline antibodies
- Active: Elevated antibodies
- Severe: High-titer antibodies
- Action Points
- Negative: Consider other diagnoses
- Borderline: Monitor and repeat
- Positive: Biopsy consideration
- Strong positive: Urgent referral
Follow-up Recommendations:
- Negative: Routine follow-up if high risk
- Borderline: Repeat in 3-6 months
- Positive: Gastroenterology referral
- Monitor every 3-6 months on GFD
- Annual testing once normalized
