Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (948 page)

   Cachexia and anorexia

Decreased In

   After eating

   Limitations

   This test is not available routinely in many commercial clinical laboratories.

GLIADIN (DEAMIDATED) ANTIBODIES, IgG AND IgA

   Definition

   ELISA-based deamidated gliadin (DGP) antibody assay is a more useful test in the diagnosis of celiac disease than the native gliadin antibody assays. DGP assays seem to be equivalent to, but not better than, tissue transglutaminase– IgA (TTG-IgA); however, DGP assays may have additive benefits in celiac screening because the combination of the two tests can increase the sensitivity without actually lowering the specificity. The DGP test also may be beneficial in circumstances when the TTG results are indeterminate. In addition, among young children, it seems to appear before TTG and to resolve faster in the context of gluten withdrawal.

   Other names: DGP, gliadin IgA, and IgG.

   
Normal range:

   Negative: ≤19 U

   Weak positive: 20–30 U

   Positive: ≥31 U

   Use

   For initial evaluation for celiac disease in IgA-deficient population