Screening for Celiac Disease in an Asymptomatic First-Degree Relative
Order tissue transglutaminase IgA (tTG-IgA) test with documentation of normal total serum IgA levels for this 18-month-old first-degree relative of a celiac disease patient. 1
Rationale for Screening
- All first-degree relatives of confirmed celiac disease patients should be offered screening, regardless of symptoms, because they carry significantly elevated risk compared to the general population 1
- The child is at appropriate age for reliable serologic testing (18 months old), making this an ideal time to perform initial screening 1
- Normal growth and weight do not exclude celiac disease, as many children with celiac disease are asymptomatic or have subclinical presentations 2, 3
Why Not Reassurance Alone
- Simply reassuring the family without screening misses a critical opportunity for early detection in a high-risk individual 1
- First-degree relatives have substantially higher prevalence of celiac disease than the general population, justifying systematic screening even in asymptomatic individuals 4
- Undiagnosed celiac disease can lead to long-term complications including nutritional deficiencies, growth impairment, and increased risk of other autoimmune conditions 2
Why Not Start Gluten-Free Diet
- Starting a gluten-free diet before confirmed diagnosis imposes significant psychosocial and nutritional burden on the patient and family 1
- A premature gluten-free diet makes subsequent diagnostic testing unreliable, as both serology and biopsy require ongoing gluten exposure for accuracy 3
- Gluten-free dietary therapy should be initiated only after celiac disease is confirmed by positive serology and, in most cases, duodenal biopsy 1, 5
Appropriate Testing Protocol
- Measure IgA tissue transglutaminase (tTG-IgA) antibodies with documentation of normal total serum IgA levels as the primary screening test 1, 4
- If IgA deficiency is present, use IgG tTG and deamidated gliadin peptide antibodies instead 1, 4
- Anti-tTG IgA has superior sensitivity (87.5%) and specificity (95.4%) for celiac disease screening in young children 6, 7
Follow-Up Based on Results
If screening is negative:
- Repeat serologic screening 2 years after the initial test and again 5 years later 1, 4
- Consider more frequent screening if the child develops symptoms suggestive of celiac disease (diarrhea, impaired growth, abdominal pain) or acquires another autoimmune condition such as type 1 diabetes 1, 4
- Monitor growth parameters closely, as poor growth may indicate undiagnosed celiac disease 1, 5
If screening is positive:
- Duodenal biopsy remains essential for diagnosis confirmation before initiating dietary changes 1, 5
- Obtain at least 4-6 biopsy specimens from the second part of the duodenum or beyond, including the duodenal bulb 1, 4
- After biopsy confirmation, initiate strict gluten-free diet and refer to a dietitian experienced in celiac disease management 1, 5
Common Pitfalls to Avoid
- Do not perform testing after starting a gluten-free diet, as this will render both serology and biopsy unreliable 3
- Do not skip total serum IgA measurement, as IgA deficiency occurs in approximately 2-3% of celiac disease patients and will cause false-negative tTG-IgA results 1, 4
- Do not assume normal growth excludes celiac disease, as subclinical presentations are common in screened populations 2, 3