The overlap between type 1 diabetes and celiac disease in children and the role of tTG-IgA positivity in endoscopy decision.

Introduction: Celiac Disease (CD)-related antibody positivity in children with Type 1 Diabetes (T1D) may fluctuate and become negative spontaneously. There are uncertainties about the optimal tTG-IgA titre and timing of endoscopy in the diagnosis of CD, and this study aimed to contribute to the debate on the tTGA-IgA threshold titre for endoscopy decisions in children with T1D.

Methods: The data of 991 children with T1D who had undergone serologic evaluation for CD were analysed retrospectively. The tTG-IgA positivity rate and the upper limit of normal (ULN) tTG-IgA positivity were assessed. Participants were grouped according to the frequency, course and test results of tTG-IgA tests. Those with and without histopathologic diagnosis of CD by endoscopic biopsy were compared in terms of tTG-IgA screening time and tTG-IgA predictive values.

Results: In 10.2% (n:101) of all cases, tTG-IgA antibody was positive and endoscopic biopsy was performed in 68.3% (n:69) of these cases. Of all cases, 4.3% (n:43) were diagnosed with CD by endoscopic biopsy. A tTG-IgA titre of 7xULN and above was found to be the best predictive value for the diagnosis of CD with 79.1% sensitivity, 80.8% specificity 87.2% positive predictive value and 70% negative predictive value.

Conclusions: Approximately 10% of antibody positive cases showed fluctuating and low titre positivity, and no CD was detected by endoscopic biopsy in the group with fluctuating antibody course. The results of our study suggest that endoscopy in children with tTG-IgA levels 7xULN or above may prevent both false positive results and missed cases.