Thyroid Autoantibody Test
Introduction to Thyroid Autoantibody Testing
Thyroid autoantibody testing is crucial for diagnosing autoimmune thyroid disorders in pediatric populations. These tests detect antibodies that target specific thyroid proteins, indicating autoimmune activity against the thyroid gland.
Key Points:
- Essential for diagnosing Hashimoto's thyroiditis and Graves' disease
- Common in children with family history of thyroid disorders
- Higher prevalence in children with other autoimmune conditions
- Critical for monitoring disease progression and treatment response
Anti-TPO (Thyroid Peroxidase) Antibodies
Clinical Significance:
- Primary marker for Hashimoto's thyroiditis
- Present in 95% of Hashimoto's cases
- Can precede clinical symptoms by years
- May indicate future thyroid dysfunction risk
Testing Specifications:
- Sample Type: Serum
- Normal Range: < 35 IU/mL (varies by laboratory)
- Collection: No special preparation needed
- Processing Time: 24-48 hours
Clinical Indications:
- Unexplained goiter
- Growth failure
- Fatigue and weight gain
- Family history of thyroid disorders
- Down syndrome screening
- Type 1 diabetes monitoring
Anti-Thyroglobulin (Anti-Tg) Antibodies
Clinical Significance:
- Secondary marker for autoimmune thyroid disease
- Present in 60-70% of Hashimoto's cases
- Used in conjunction with Anti-TPO
- Important for thyroid cancer monitoring
Testing Specifications:
- Sample Type: Serum
- Normal Range: < 20 IU/mL (varies by laboratory)
- Collection: Fasting not required
- Processing Time: 24-48 hours
Clinical Applications
Primary Uses:
- Diagnosis of autoimmune thyroid disorders
- Risk assessment in high-risk populations
- Disease monitoring and treatment response
- Screening in associated conditions
High-Risk Groups Requiring Screening:
- Children with Type 1 diabetes
- Down syndrome patients
- Turner syndrome patients
- First-degree relatives of AITD patients
- Children with other autoimmune conditions
Result Interpretation
Anti-TPO Interpretation:
- Negative (< 35 IU/mL): No evidence of autoimmune thyroid disease
- Borderline (35-50 IU/mL): Monitor and repeat in 3-6 months
- Positive (> 50 IU/mL): Consistent with autoimmune thyroid disease
- Strongly Positive (> 500 IU/mL): High risk of progression to hypothyroidism
Anti-Tg Interpretation:
- Negative (< 20 IU/mL): No evidence of autoimmune thyroid disease
- Borderline (20-40 IU/mL): Monitor and repeat in 3-6 months
- Positive (> 40 IU/mL): Supportive of autoimmune thyroid disease
Combined Interpretation:
- Both Positive: Strong evidence of autoimmune thyroid disease
- TPO Positive/Tg Negative: Likely autoimmune thyroid disease
- TPO Negative/Tg Positive: Possible early disease or false positive
- Both Negative: Autoimmune thyroid disease unlikely
