Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

DAGL
89029
Clinical References: 1. Green PH, Cellier C: Celiac disease. New Engl J Med 2007;357:1731-1743
2. Green PH, Jabri B: Celiac disease. Annu Rev Med 2006;57:207-221 3. Harrison MS, Wehbi M,
Obideen K: Celiac disease: More common than you think. Cleve Clin J Med 2007;74:209-215 4. Dale JC,
Homburger HA, Masoner DE, et al: Update on celiac disease: New standards and new tests. Mayo
Communique 2008;33(6):1-9 5. Rashtak S, Ettore MW, Homburger HA, et al: Comparative usefulness of
deamidated gliadin antibody measurements in the diagnosis of celiac disease. Clin Gastroenterol Hepatol
2008 Apr;6(4):426-432 6. Sugai E, Vazquez H, Nachman F, et al: Accuracy of testing for antibodies to
synthetic gliadin-related peptides in celiac disease. Clin Gastroenterol Hepatol 2006;4:1112-1117
Gliadin (Deamidated) Antibody, IgA, Serum
Clinical Information: Celiac disease (gluten-sensitive enteropathy, celiac sprue) results from an
immune-mediated inflammatory process that occurs in genetically susceptible individuals following
ingestion of wheat, rye, or barley proteins.(1) The inflammation in celiac disease occurs primarily in the
mucosa of the small intestine, which leads to villous atrophy.(1) Common clinical manifestations related
to gastrointestinal inflammation include abdominal pain, malabsorption, diarrhea, and/or constipation.(3)
Clinical symptoms of celiac disease are not restricted to the gastrointestinal tract. Other common
manifestations of celiac disease include failure to grow (delayed puberty and short stature), iron
deficiency, recurrent fetal loss, osteoporosis, chronic fatigue, recurrent aphthous stomatitis (canker sores),
dental enamel hypoplasia, and dermatitis herpetiformis.(4) Patients with celiac disease may also present
with neuropsychiatric manifestations including ataxia and peripheral neuropathy, and are at increased risk
for development of non-Hodgkin lymphoma.(1,2) The disease is also associated with other clinical
disorders including thyroiditis, type I diabetes mellitus, Down syndrome, and IgA deficiency.(1,3) Celiac
disease tends to occur in families; individuals with family members who have celiac disease are at
increased risk of developing the disease. Genetic susceptibility is related to specific HLA markers. More
than 97% of individuals with celiac disease in the United States have DQ2 and/or DQ8 HLA markers
compared to approximately 40% of the general population.(3) A definitive diagnosis of celiac disease
requires a jejunal biopsy demonstrating villous atrophy.(1-3) Given the invasive nature and cost of the
biopsy, serologic tests may be used to identify individuals with a high probability of having celiac disease.
Because no single laboratory test can be relied upon completely to establish a diagnosis of celiac disease,
those individuals with positive laboratory results should be referred for small intestinal biopsy, thereby
decreasing the number of unnecessary invasive procedures. Celiac disease is associated with a variety of
autoantibodies, including endomysial (EMA), tissue transglutaminase (tTG), and deamidated gliadin
antibodies.(4) Although the IgA isotype of these antibodies usually predominates in celiac disease,
individuals may also produce IgG isotypes, particularly if the individual is IgA deficient.(2) The most
sensitive and specific serologic tests are tTG and deamidated gliadin antibodies. Testing for IgA and IgG
antibodies to unmodified gliadin proteins is no longer recommended because of the low sensitivity and
specificity of these tests for celiac disease; however, recent studies have identified specific B-cell epitopes
on the gliadin molecule that, when deamidated by the enzyme tTG, have increased sensitivity and
specificity for celiac disease.(5,6) The tests for deamidated gliadin antibodies, IgA and IgG, replace the
older gliadin antibody tests, which have been discontinued at Mayo Clinic. The sensitivity and specificity
of DGLDN/89031 Gliadin (Deamidated) Antibodies Evaluation, IgG and IgA, Serum for untreated,
biopsy-proven celiac disease were comparable to test TSTGP/83671 Tissue Transglutaminase (tTG)
Antibodies, IgA and IgG Profile, Serum in a study conducted at Mayo Clinic.(5) The treatment for celiac
disease is maintenance of a gluten-free diet (1-3) In most patients who adhere to this diet, levels of
associated autoantibodies decline and villous atrophy improves. This is typically accompanied by an
improvement in clinical symptoms. For evaluation purposes, all serologic tests ordered for the diagnosis
of celiac disease should be performed while the patient is on a gluten-containing diet. Once a patient has
initiated the gluten-free diet, serologic testing may be repeated to assess the response to treatment. In
some patients, it may take up to 1 year for antibody titers to normalize. Persistently elevated results
suggest poor adherence to the gluten-free diet or the possibility of refractory celiac disease.(1) See Celiac
Disease Diagnostic Testing Algorithm in Special Instructions for the recommended approach to a patient
suspected of celiac disease. An algorithm is available for monitoring the patient's response to treatment,
see Celiac Disease Routine Treatment Monitoring Algorithm in Special Instructions. For your
convenience, we recommend utilizing cascade testing for celiac disease. Cascade testing ensures that
testing proceeds in an algorithmic fashion. The following cascades are available; select the appropriate
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