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
If you have any questions or concerns please feel free to contact Dr.
Heightchew at 484.476.2619 or Annemarie Brewer, Immunology Supervisor,
For more information, call 1.866.CALL.MLH.