Endomysium IgA (IFA)
Sample: Serum
Schedule: Daily (IFA Immunofluoresence)
Units: TITER
Range: Negative
Remarks: Endomysial antivodies are useful in the diagnosis of gluten-sensitive enteropathies. The presence of these antibodies to any one or a combination of three serum markers (gliadin, reticulin, and endomysium) is associated with a history of gastrointestinal disorders and is consistent with a diagnosis of celiac disease or dermatitis herpetiformis, which are caused by sensitivity to gluten.
The Tissue Transglutaminase antibody test is considered to have more sensitivity than the anti-gliadin and the anti-endomysium as screening tests for celiac disease. A positive Tissue Transglutaminase test that changes to negative after a gluten free diet is considered supportive evidence. The definitive diagnosis is done with small bowel biopsy. Children must be ingesting gluten for the small intestine to have the characteristic histological changes so clinicians should not prescribe a gluten free diet prior to testing being completed. Strict avoidance of gluten in the diet will control disease activity, and antibodies to serum markers will disappear with time.
Wheat gluten is a mixture of polypeptides that are rich in glutamine residues. In the intestinal mucosa the enzyme transglutaminase removes an amino group from the digested peptides either cross-linking with another polypeptide or creating a free glutamate residue. In patients with the type of major histocompatibility complex that presents small peptides with glutamate residues, the antigen-presenting cells in the lamina propria of the small intestine activates the CD4 T cells, resulting in inflammation that causes diarrhea and malabsorption. Autoantibodies to the tissue transglutaminase are a marker of this disorder (called celiac disease).
