PhenX - celiac sprue assay protocol 190301

Celiac sprue assay proto

Definition

This protocol uses two-step serologic testing of serum to determine the presence of antihuman recombinant tissue transglutaminase (TTG) and endomysial antibody (EMA). When both tests are positive, the subject is notified that they are positive for celiac sprue. The test is most accurate if patients have not been on a gluten-free diet in the weeks leading up to the assay, as a gluten-free diet may cause the serologic assays to normalize in many patients. It is important that the patients screened with this laboratory assay are eating a diet that contains dietary sources of gluten in order for the assay to be most accurate. Sources of dietary gluten include the grains wheat, rye, and barley. The Gastrointestinal Working Group (WG) also recommends performing the immunoglobulin A (IgA) and immunoglobulin G (IgG) antibody tests for more sensitivity. The National Health and Nutrition Examination Survey (NHANES) uses red-top tubes to collect 0.5 ml serum for the antihuman recombinant tissue transglutaminase (TTG)/ endomysial antibody (EMA) bioassay. However, the Gastrointestinal Working Group recommends consulting the laboratory that will perform the bioassay regarding the appropriate collection tubes to use.