No-biopsy Approach in Celiac Disease: Cut-off Points for IgA Anti-tissue Transglutaminase Assays

No-biopsy Approach for the Diagnosis of Celiac Disease: Definition of Cut-off Points for Different IgA Anti-tissue Transglutaminase Assays

The main objective of this multicenter and observational study is to define the optimal threshold of different commercially available IgA anti-transglutaminase (tTG-IgA) antibody assays for celiac disease diagnosis (CD) avoiding the need for an intestinal biopsy.

The main questions to be answered are:

• Is the anti-tTG-IgA titer cut-off above 10 times the upper limit of normal (ULN) useful in all anti-tTG IgA assays?
• Is the diagnostic performance of the newly defined cut-offs of anti-tTG-IgA the same in all the evaluated assays?
• Is the dynamic of the anti-tTG-IgA levels after the introduction of the gluten-free diet (GFD) similar across the different assays included in the study?

This is a prospective multicenter study that will enroll pediatric and adult patients with new-onset CD during the years 2023 and 2024. Serum from these patients will be collected for the determination of anti-tTG-IgA according to the local methodology (participating hospital) and by the anti-tTG IgA assays most commonly used in our country, which will be centralized in the same reference center (Hospital Universitario La Paz).

Inclusion criteria:

• Patients, on gluten-containing diet, with TGt-IgA antibodies > Upper Limit of Normal (ULN) and intestinal biopsy confirming celiac disease (CD).
• Patients with TCRγδ+ >10% combined with decrease NK-like intraepithelial lymphocytes in the intestinal epithelium.
• Paediatric patients who meet ESPGHAN criteria (TGt-IgA antibodies >10xULN) without duodenal biopsy performed.

Exclusion criteria:

• Patients already diagnosed with CD.
• Patients who refused duodenal biopsy.
• Patients with primary or secondary immunodeficiencies.
• Patients with malignancy.
• Recruited patients whose remaining serum cannot be sent to the reference centre, whose biopsies are of poor quality or who nod not sign the informed consent from.