From the Guidelines
Celiac disease screening should start with tissue transglutaminase antibody (tTG-IgA) and total serum IgA tests, as recommended by the most recent and highest quality study 1. When it comes to celiac disease screening, blood tests are the initial step in diagnosis.
Key Tests
- Tissue transglutaminase antibody (tTG-IgA) is the preferred test for individuals over two years old, as stated in the guidelines by the American College of Gastroenterology 1.
- Total serum IgA is also necessary to rule out IgA deficiency.
- Additional tests, such as deamidated gliadin peptide antibodies (DGP IgA and IgG) and endomysial antibodies (EMA), may be used as confirmatory tests.
Pre-Test Requirements
- Patients should continue eating gluten-containing foods before the test to avoid false negative results, with a recommended gluten intake of at least 10g daily for 6-8 weeks prior to testing.
Diagnosis and Next Steps
- A definitive diagnosis typically requires an intestinal biopsy, but the most recent study 1 suggests that biopsy-avoidance strategies may be considered in certain cases.
- Testing is recommended for people with symptoms like chronic diarrhea, weight loss, abdominal pain, or those with a family history of celiac disease.
- If blood tests are positive, a referral to a gastroenterologist for an endoscopic biopsy or further investigation may be necessary to confirm the diagnosis before starting a gluten-free diet.
Important Considerations
- The accuracy of serological tests for diagnosing celiac disease is highly sensitive and specific, as shown in the systematic review with meta-analysis 1.
- Guidelines have begun to move towards biopsy-avoidance strategies for celiac disease in children and adults, as seen in the British Society of Gastroenterology's interim guidance 1.
From the Research
Celiac Screen Blood Tests
- Celiac disease is an immune-mediated, multisystem disorder that affects genetically susceptible individuals who are exposed to gluten-containing grains such as wheat, barley, and rye 2.
- The condition can develop at any age and presents with a variety of manifestations such as diarrhea, weight loss, abdominal pain, bloating, malabsorption, and failure to thrive.
- Immunoglobulin A tissue transglutaminase serologic testing is the recommended initial screening for all age groups 2.
Types of Blood Tests
- Immunoglobulin A tissue transglutaminase (tTG) antibodies are a hallmark for celiac disease (CD) 3.
- Antiendomysial antibodies (EMA) are also used to diagnose celiac disease 4, 5.
- Antigliadin antibodies (AGA) can be used to diagnose celiac disease, but they are not as sensitive or specific as tTG or EMA 4.
Sensitivity and Specificity of Blood Tests
- The sensitivity and specificity of tTG antibodies are high, with a sensitivity of 100% and a specificity of 94% in one study 4.
- The sensitivity and specificity of EMA antibodies are also high, with a sensitivity of 100% and a specificity of 100% in one study 4.
- However, the sensitivity of tTG and EMA antibodies in detecting persistent villous atrophy in patients on a gluten-free diet is low, with a sensitivity of 0.50 for tTG and 0.45 for EMA 5.
Comparison of Different Assays
- Different tissue transglutaminase IgA assays can give different results, with some assays being more sensitive than others 3.
- The use of different assays can affect the monitoring of patients with celiac disease on a gluten-free diet, with some assays detecting suboptimal treatment response more accurately than others 3.