Why Celiac Serology Needs To Be Looked At Differently in Children with Type 1 Diabetes

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A recent study (M Wessels et al. J Pediatr 2020; 223: 87-92. Raising the Cut-Off Level of Anti-Tissue Transglutaminase Antibodies to Detect Celiac Disease Reduces the Number of Small Bowel Biopsies in Children with Type 1 Diabetes: A Retrospective Study) recommends changing the approach to celiac disease (CD) diagnosis in children with Type 1 Diabetes Mellitus (T1DM).

Background: The prevalence of CD among patients with T1DM is between 3-10%

Using a retrospective observational cohort with 63 children, the authors recommend raising the cut-off from performing biopsies from 3 times the ULN to 11 times ULN.

Here’s why:

  • This change in increases the specificity from 36% to 73% while reducing sensitivity from 96% to 87%.  In addition, this improves the positive predictive value from 88% to 94%, but lowered negative predictive value from 67% to 53%.  Overall, this leads to a reduction in “unnecessary biopsies.”
  • The authors note that while the serology sensitivity is reduced, it is still acceptable and justified because “normalization of elevated TG2A  can occur in up to one-third of patients.”
  • Another finding from this cohort was that 55% of children with Marsh 0 or 1 histology were symptomatic, indicating that symptoms are not specific for CD.

While the authors have recommended a higher threshold and advocated for repeating serology ~3 months later in those with lower titers, the associated editorial by Stefano Guandalini makes the following points:

  1. Raising the titer threshold would leave 13% of patients with celiac disease undiagnosed (or at least with a delay in diagnosis)
  2. “For lower titers, the physician will have to apply his or her knowledge and conscience in each individual case…we must be mindful of the serious risk of missing too many patients with celiac disease by applying a high threshold, a risk probably outweighing that of an unnecessary biopsy.”

My take: This study shows that in children with T1DM who have abnormal lower-value celiac serology, a careful discussion with parents is needed about the merits of endoscopy or deferring until persistent positivity.

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