CD79A and Atrophy: The diagnostic performance of the ≥10×ULN tTG-IgA threshold for detecting VA was confirmed by AUROC of 0.737, CI 0.646-0.827, <i>p</i> < 0.001, with a sensitivity of 55.0% and a specificity of 84.6%, a PPV of 90.2% and a NPVof 42.3% (33/78), underscoring that while the ≥10×ULN tTG-IgA threshold is highly specific for atrophy, lower titers do not reliably exclude it in adults.