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 (Option B).
Rationale for Screening
First-degree relatives of patients with celiac disease have a 10-15% lifetime risk of developing the condition, making them a high-risk population that warrants serologic screening 1, 2.
The American Gastroenterological Association specifically identifies first-degree relatives as a population requiring screening, even when asymptomatic 1.
While normal growth and weight are reassuring signs that make active celiac disease unlikely at this time, they do not eliminate the need for screening in this high-risk population 2.
Recommended Testing Strategy
The initial screening should include IgA tissue transglutaminase (tTG-IgA) combined with total IgA measurement, which has a sensitivity of 90-96% and specificity greater than 95% 1.
Total IgA levels must be verified to rule out selective IgA deficiency, which occurs in 1-3% of celiac disease patients and could affect test interpretation 3.
If IgA deficiency is detected, IgG-based tests (IgG tTG or IgG EMA) should be used instead 1.
Critical Pre-Testing Requirement
The child must remain on a gluten-containing diet until testing is complete to avoid false-negative results 1, 2.
Never start a gluten-free diet before completing the diagnostic workup, as this leads to false-negative serology and inconclusive biopsies 3.
Why Reassurance Alone Is Inadequate
Although the child is currently asymptomatic with normal growth, celiac disease can be subclinical and still cause long-term complications if undetected 4, 5.
Current guidelines do not support simply reassuring parents without screening when a first-degree relative has celiac disease 1, 2.
Early detection allows for intervention before symptoms or complications develop, including malabsorption, nutritional deficiencies, and associated autoimmune conditions 3.
Why Starting a Gluten-Free Diet Is Inappropriate
A gluten-free diet should never be initiated without diagnostic confirmation, as it represents a significant dietary burden and requires lifelong adherence 3, 5.
Starting the diet prematurely would make future diagnostic testing unreliable and potentially require a prolonged gluten challenge (at least three slices of wheat bread daily for 1-3 months) 3.
Biopsy confirmation is recommended, especially in asymptomatic children, before prescribing significant dietary changes 6, 3.
Parent Education Points
Educate parents about symptoms that would warrant immediate testing if they develop, including poor weight gain or growth failure, unexplained irritability or behavioral changes, and gastrointestinal symptoms 1, 2.
If the child develops type 1 diabetes in the future, immediate screening with tTG-IgA would then be indicated per American Diabetes Association guidelines 2, 6.
If growth parameters deviate from normal trajectory or symptoms suggestive of celiac disease emerge, screening should be reconsidered 2.
Follow-Up Based on Results
If tTG-IgA is positive: Proceed to upper endoscopy with duodenal biopsy (at least 6 specimens from the second part of the duodenum or beyond) for histological confirmation using Marsh classification 3.
If tTG-IgA is negative: Reassure parents but maintain vigilance for symptom development, as celiac disease can develop at any age 4, 5.