Screening for Celiac Disease in Asymptomatic First-Degree Relatives
Order tissue transglutaminase IgA (tTG-IgA) test now, with documentation of normal total serum IgA levels. This 18-month-old child is at significantly elevated risk (approximately 10%) for developing celiac disease due to having an affected sibling, and current guidelines recommend screening all first-degree relatives regardless of symptoms 1, 2.
Why Screen This Asymptomatic Child?
First-degree relatives represent the highest risk group for celiac disease, with prevalence rates of 7.5-10% compared to approximately 1% in the general population 1, 3, 4. The risk is even higher when the affected relative is a sibling rather than a parent 5.
Key Evidence Supporting Screening:
Disease severity is independent of symptoms: A 2023 study demonstrated that 51% of children diagnosed through family screening were asymptomatic, yet their histologic disease severity was identical to symptomatic patients 6. This means waiting for symptoms would allow significant intestinal damage to occur.
Early detection prevents complications: Undiagnosed celiac disease leads to nutritional deficiencies, growth impairment, and increased long-term mortality risk 7, 5. The child's current normal growth does not exclude celiac disease 6.
Guideline consensus: The North American Society for Pediatric Gastroenterology, Hepatology and Nutrition explicitly recommends screening asymptomatic first-degree relatives 2, and the American Gastroenterological Association states all first-degree relatives should be offered screening 1.
The Appropriate Screening Test
Measure IgA tissue transglutaminase (tTG-IgA) antibodies with documentation of normal total serum IgA levels 8, 1. This is the primary screening test with 90.7% sensitivity and 87.4% specificity in adults, and similar performance in children 3.
Important Testing Considerations:
Check total serum IgA simultaneously: If the child has IgA deficiency (present in 2-3% of celiac patients), the tTG-IgA will be falsely negative 1, 2.
If IgA deficient: Use IgG-based tests (IgG tTG and deamidated gliadin peptide antibodies) instead 8, 1.
Positive results require biopsy confirmation: Before imposing a lifelong gluten-free diet, duodenal biopsy is essential to confirm the diagnosis, especially in asymptomatic children 8, 1, 2.
Why Not Just Reassure?
Reassurance alone is inappropriate because:
- The 10% risk is substantial and clinically significant 1, 3
- Asymptomatic disease can cause silent complications including growth failure, bone disease, and nutritional deficiencies 7, 5
- Current normal growth does not exclude celiac disease 6
- Guidelines explicitly recommend against a "wait and see" approach in this high-risk population 1, 2
Why Not Start a Gluten-Free Diet Empirically?
Starting a gluten-free diet without confirmed diagnosis is contraindicated because:
- It imposes significant psychosocial and nutritional burden on the child and family 1
- Once on a gluten-free diet, serologic testing becomes unreliable, making future diagnosis difficult 3
- Biopsy confirmation is required before committing to lifelong dietary restriction 8, 1, 2
- The challenging dietary restrictions of both managing a gluten-free diet in a toddler without confirmed disease is unjustified 8
Follow-Up Screening Protocol
If the initial screen is negative, this child will need ongoing surveillance:
- Repeat screening at 2 years after the initial test 8, 1
- Screen again at 5 years from initial testing 8, 1
- More frequent screening if symptoms develop (diarrhea, poor growth, abdominal pain, irritability) or if the child develops another autoimmune condition such as type 1 diabetes 8, 1
Consider HLA Typing
HLA-DQ2/DQ8 genetic testing can be considered at initial screening to stratify future risk 1. If both HLA-DQ2 and HLA-DQ8 are absent, celiac disease is effectively ruled out and eliminates the need for future screening 1. However, this is optional and not required for initial management.
Common Pitfalls to Avoid
- Don't wait for symptoms: 51% of family-screened children are asymptomatic at diagnosis yet have significant disease 6
- Don't skip total IgA measurement: Isolated tTG-IgA without total IgA can miss IgA-deficient patients 1, 2
- Don't start gluten-free diet before testing: This invalidates both serologic and histologic diagnosis 1, 3
- Don't assume normal growth excludes disease: Histologic severity is independent of clinical presentation 6