Effective 7/27/10, Main Line Health Laboratories, Inc. will offer the option to order a sequence of serologic testing for gluten-sensitive enteropathy (GSE), also called celiac disease. This sequence of tests will be orderable as ‘CELIAC ANTIBODY WITH REFLEX’ and will be comprised of IgA anti-Tissue Transglutaminase (IgA anti-TTG) followed by total IgA level and IgG anti-Tissue Transglutaminase (IgG anti-TTG) when appropriate. This testing algorithm was developed in cooperation with the division of Gastroenterology and the Paoli Hospital Celiac Center.
IgA anti-TTG is the single best serologic test for celiac disease, with a reported sensitivity >95% and specificity >90%. However, a small percentage of patients with celiac disease may give a false negative result due to IgA deficiency. In this population of patients, the appropriate test for celiac disease is IgG anti-TTG. When ordered as ‘CELIAC ANTIBODY WITH REFLEX’ a negative IgA anti-TTG result (defined as <20 units) will prompt measurement of total IgA levels. If total IgA is low (defined as < 85 mg/dL), then testing for IgG anti-TTG will be performed. Alternatively, if IgA anti-TTG is positive, no further testing will be performed. If total IgA levels are normal, testing for IgG anti-TTG will not be initiated upon a negative IgA anti-TTG result (see flow chart on the back of this memo).
The intent of this sequential testing is to ensure that the most appropriate serologic testing is performed for each patient, thereby minimizing false-negative results which could lead to a delay in diagnosis of celiac disease. Celiac serology with reflex testing is being offered as an option; each of the assays will continue to be available individually.
If you have any questions or concerns please feel free to contact Dr. Heightchew at 484-476-2619 or Annemarie Brewer, Immunology Supervisor, at 484-476-8408.
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