American College of Gastroenterology Guidelines: When to Test for Celiac Disease
Testing for celiac disease should be performed in persons with4
- Symptoms, signs, or laboratory evidence suggestive of malabsorption, such as chronic diarrhea with weight loss, steatorrhea, postprandial abdominal pain and bloating
- Symptoms, signs, or laboratory evidence for which celiac disease is a treatable cause
- A first-degree family member who has a confirmed diagnosis of celiac disease if they show possible signs or symptoms or laboratory evidence of celiac disease
- Type 1 diabetes mellitus if there are any digestive symptoms, or signs, or laboratory evidence suggestive of celiac disease
Testing should be considered for4
- Asymptomatic relatives with a first-degree family member who has a confirmed diagnosis of celiac disease
- Individuals with unexplained elevations of serum aminotransferase levels
How the Laboratory Can Help
Quest Diagnostics offers tests for the different antibodies that are associated with celiac disease and comprehensive testing panels that may help to more quickly establish a diagnosis of celiac disease.
The Celiac Disease Comprehensive Panel with Gliadin Antibody (IgG) (test code 36336) begins by testing specimens for tTG IgA (test code 8821). Specimens positive for tTG IgA are tested for EMA IgA (test code 15064), which may increase specificity for celiac disease. This panel also tests all specimens for total IgA (test code 539). A total IgA level below the reference range is suggestive of IgA deficiency and reflexes to IgG-based tests (tTG IgG [test code 11070] and DGP IgG [test code 11212]); these tests are generally less sensitive than tTG IgA testing for celiac disease but are useful in the context of IgA deficiency.
The Celiac Disease Comprehensive Panel with Gliadin Antibodies (Age 5 and under) (test code 36331) is used to assist in the diagnosis of celiac disease in children ≤5 years old. All specimens are initially tested for DGP IgA and DGP IgG (test code 8889), in addition to tTG IgA (test code 8821), which has reduced sensitivity in young children. Specimens positive for tTG IgA are tested for EMA IgA (test code 15064). This panel also evaluates all specimens for total IgA (test code 539); a total IgA level below the reference range is suggestive of IgA deficiency and reflexes to tTG IgG (test code 11070).
The HLA Typing for Celiac Disease (test code 17135) assay tests for HLA alleles associated with celiac disease (HLA-DQ2 and HLA-DQ8). A negative result is useful for ruling out celiac disease in some situations, such as patients with discrepant celiac-specific serology and small intestine biopsy findings.4
Quest also offers panels to help diagnose conditions with similar symptoms to celiac disease such as the Inflammatory Bowel Disease Differentiation Panel (test code: 16503) which can help distinguish Crohn’s disease from ulcerative colitis. The panel includes: ANCA Screen with Reflex to ANCA Titer (test code 70171); Myeloperoxidase Antibody (MPO) (test code 8796); Proteinase-3 Antibody (test code 34151); Saccharomyces cerevisiae Antibodies (ASCA) (IgG) (test code 10294); Saccharomyces cerevisiae Antibodies (ASCA) (IgA) (test code 10295).
The Calprotectin, Stool (test code: 16796) assay can also help differentiate IBD (Crohn’s disease, ulcerative colitis) from celiac disease and IBS.
Quest also offers food allergy testing, with reflex to component testing. Specific IgE testing for allergen components can help identify the specific protein in a food that is causing the allergic reaction. Knowing the specific protein causing the reaction can help determine a person’s risk of a severe systemic reaction vs a mild, localized reaction.
Panel components can be ordered separately. Reflex tests are performed at an additional charge and are associated with an additional CPT code.