For individuals with IgA deficiency: Evaluating patients suspected of having celiac disease, including patients with compatible clinical symptoms, patients with atypical symptoms, and individuals at increased risk (family history, previous diagnosis with associated disorder, positivity for HLA DQ2 and/or DQ8 Screening test for dermatitis herpetiformis, in conjunction with an endomysial antibody test Monitoring response to gluten-free diet in patients with dermatitis herpetiformis and celiac disease. Ref. value: <6.0 U/mL (negative) 6.0-9.0 U/mL (weak positive) >9.0 U/mL (positive)