Objectives: The diagnosis of celiac disease (CD) is based on the histological identification of gluten-sensitive enteropathy and detection of anti-tissue transglutaminase antibodies (tTGA) and/or endomysial antibodies. Serial measurements of tTGA are now recommended as a follow-up strategy to monitor compliance with a gluten-free diet (GFD). We evaluated the performances of a quantitative radiobinding assay (RBA) of tTGA immunoglobulin A at diagnosis and during monitoring of GFD in pediatric CD.
Methods: Eighty children with confirmed CD were selected. Levels of serum tTGA measured by RBA and a commercial enzyme-linked immunosorbent assay (ELISA) were compared at diagnosis. The relation between RBA-tTGA levels and histological damage was analyzed, as well as the time course of tTGA clearance during GFD.
Results: Both RBA and ELISA showed high sensitivity and specificity for tTGA detection at diagnosis. There was no relation between RBA-tTGA levels at diagnosis and severity of mucosal damage. Upon initiation of GFD, the rate of RBA-tTGA positivity declined slower than that of endomysial antibodies positivity, with >50% of the children still tTGA positive at year 5; however, tTGA levels decreased rapidly during the first year of GFD and more slowly thereafter. Children who seroreverted had lower tTGA levels at diagnosis (2080±1554 cpm) than those who remained tTGA positive throughout follow-up (3688±1435 cpm).
Conclusions: The high sensitivity of RBA is likely responsible for higher tTGA positivity rates during GFD than previously reported with ELISA. A decreasing trend for tTGA levels may represent a better surrogate marker of compliance with GFD than absolute normal tTGA levels.