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Test ID: CDGF Celiac Disease Gluten-Free Cascade, Serum and Whole Blood

Reporting Name

Celiac Disease Gluten-Free Cascade

Useful For

Evaluating patients suspected of having celiac disease who are currently (or were recently) on a gluten-free diet

Clinical Information

Celiac disease (gluten-sensitive enteropathy, celiac sprue) results from an immune-mediated inflammatory process following ingestion of wheat, rye, or barley proteins that occurs in genetically susceptible individuals.(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 constipation.(2) 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.(3) 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 with 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 and genetic laboratory tests may be used to identify individuals with a high probability of having celiac disease. Subsequently, those individuals with positive laboratory results should be referred for small intestinal biopsy, thereby decreasing the number of unnecessary invasive procedures. In terms of serology, celiac disease is associated with a variety of autoantibodies, including endomysial, 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.

 

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 (see Celiac Disease Routine Treatment Monitoring Algorithm in Special Instructions). This is typically accompanied by an improvement in clinical symptoms.

 

It should be noted that HLA typing is not required to establish a diagnosis of celiac disease. Consider ordering CDSP / Celiac Disease Serology Cascade if HLA typing is not desired or has been previously performed.

Interpretation

HLA-DQ Typing:

Approximately 90% to 95% of patients with celiac disease have the HLA-DQ2 allele; most of the remaining patients with celiac disease have the HLA-DQ8 allele. Individuals who do not carry either of these alleles are unlikely to have celiac disease. For these individuals, no further serologic testing is required. However, individuals with these alleles may not, during their lifetime, develop celiac disease. Therefore, the presence of DQ2 or DQ8 does not conclusively establish a diagnosis of celiac disease. For individuals with DQ2 and/or DQ8 alleles, in the context of positive serology and compatible clinical symptoms, small intestinal biopsy is recommended.

 

Immunoglobulin A (IgA):

Total IgA levels below the age-specific reference range suggest either a selective IgA deficiency or a more generalized immunodeficiency. For individuals with a low IgA level, additional clinical and laboratory evaluation is recommended. Some individuals may have a partial IgA deficiency in which the IgA levels are detectable, but fall below the age-adjusted reference range. For these individuals, both IgA and IgG isotypes for tTG and deamidated gliadin antibodies are recommended for the evaluation of celiac disease.

 

Tissue Transglutaminase (tTG) Antibody, IgA/IgG:

Individuals positive for tTG antibodies of the IgA and/or IgG isotype may have celiac disease and small intestinal biopsy is recommended. Negative tTG IgA and/or IgG antibody serology does not exclude a diagnosis of celiac disease, as antibody levels decrease over time in patients who have been following a gluten-free diet.

 

Gliadin (Deamidated) Antibody, IgA/IgG:

Positivity for deamidated gliadin antibodies of the IgA and/or IgG isotype is suggestive of celiac disease, and small intestinal biopsy is recommended. Negative deamidated gliadin IgA and/or IgG antibody serology does not exclude a diagnosis of celiac disease, as antibody levels decrease over time in patients who have been following a gluten-free diet.

Profile Information

Test ID Reporting Name Available Separately Always Performed
CELI2 HLA-DQ Typing Yes, (Order CELI) Yes
CDGF1 Celiac Disease Interpretation No Yes

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
TTGA Tissue Transglutaminase Ab, IgA, S Yes No
DAGL Gliadin(Deamidated) Ab, IgA, S Yes No
DGGL Gliadin(Deamidated) Ab, IgG, S Yes No
TTGG Tissue Transglutaminase Ab, IgG, S Yes No
IGA Immunoglobulin A (IgA), S Yes No

Testing Algorithm

If HLA-DQ typing is positive or equivocal for DQ2 or DQ8, then IgA, tissue transglutaminase (tTG) IgA and IgG, and deamidated gliadin IgA and IgG will be performed at an additional charge.

 

The following algorithms are available in Special Instructions:

-Celiac Disease Comprehensive Cascade

-Celiac Disease Diagnostic Testing Algorithm

-Celiac Disease Gluten-Free Cascade

-Celiac Disease Routine Treatment Monitoring Algorithm

-Celiac Disease Serology Cascade

Analytic Time

7 days

Day(s) and Time(s) Performed

IgA, tTG IgA, Gliadin IgA, Gliadin IgG, tTG IgG: Monday through Saturday; 3 p.m.

HLA-DQ Typing: Monday through Friday; 7:30 a.m.-5 p.m.

Clinical Reference

1. Green PHR, Cellier C: Medical progress: Celiac disease. N EngL J Med 2007;357:1731-1743 

2. Green PHR, Jabri J: Celiac disease. Ann Rev Med 2006;57;207-221 

3. Harrison MS, Wehbi M, Obideen K: Celiac disease: More common than you think. Cleve Clinic J Med 2007;74:209-215 

4. Update on celiac disease: New standards and new tests. Mayo Communique (2008)

Method Name

CELI2: Polymerase Chain Reaction (PCR)/Sequence-Specific Oligonucleotide Probe (SSO)

Specimen Type

Serum
Whole Blood ACD-B


Advisory Information


Cascade testing is recommended for celiac disease. Cascade testing ensures that testing proceeds in an algorithmic fashion. The following cascades are available; select the appropriate one for your specific patient situation.

-CDCOM / Celiac Disease Comprehensive Cascade: complete testing including HLA DQ

-CDSP / Celiac Disease Serology Cascade: complete testing excluding HLA DQ

-CDGF / Celiac Disease Gluten-Free Cascade: for patients already adhering to a gluten-free diet

To order individual tests, see Celiac Disease Diagnostic Testing Algorithm in Special Instructions.



Specimen Required


Both blood and serum are required.

 

Specimen Type: Blood

Container/Tube: Yellow top (ACD solution B)

Specimen Volume: 6 mL

Collection Instructions: Do not transfer blood to other containers.

 

Specimen Type: Serum

Container/Tube:

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 2 mL


Specimen Minimum Volume

Blood: 3 mL
Serum 1.5 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Serum Refrigerated (preferred) 21 days
  Frozen  21 days
Whole Blood ACD-B Refrigerated (preferred)
  Ambient 

Reference Values

HLA-DQ TYPING

Presence of DQ2 or DQ8 alleles associated with celiac disease

Test Classification

This test has been cleared, approved or is exempt by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

81376 x 2

82784-IgA (if appropriate)

83516-Deamidated gliadin IgA (if appropriate)

83516-Deamidated gliadin IgG (if appropriate)

83516-tTG IgA (if appropriate)

83516-tTG IgG (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
CDGF Celiac Disease Gluten-Free Cascade 94493-4

 

Result ID Test Result Name Result LOINC Value
DQA DQ alpha 1 94495-9
28991 Celiac Disease Interpretation 69048-7
DQB DQ beta 1 53938-7
CELIG Celiac gene pairs present? 48767-8

Forms

If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Client Test Request (T728) with the specimen.

Mayo Clinic Laboratories | Neurology Catalog Additional Information:

mml-Behavioral, mml-Movement-Disorders, mml-Neuroimmunology, mml-Pediatric, mml-Spinal-Cord, mml-Neuro-ophthalmology