Celiac Disease Diagnosis
Initial Diagnostic Testing
- The American Gastroenterological Association recommends IgA tissue transglutaminase antibody (tTG-IgA) as the primary screening test for suspected celiac disease, with high sensitivity (90-96%) and specificity (>95%) 1, 2
- Testing must be performed while the patient is on a gluten-containing diet, as positive serologic results may resolve with gluten removal 2, 3
- The American Gastroenterological Association suggests that IgA endomysial antibody (EMA-IgA) testing should be performed as a second-line test, which has slightly lower sensitivity but excellent specificity (99.6%) 1, 4
Confirmatory Testing
- Intestinal biopsy remains the gold standard for diagnosis, with characteristic histologic findings including spectrum from partial to total villous atrophy, crypt lengthening, and increased lamina propria and intraepithelial lymphocytes 1, 4
- Multiple biopsy specimens (ideally 6) should be taken from the second part of the duodenum or beyond 4
Special Considerations
- The American Gastroenterological Association recommends HLA-DQ2 and HLA-DQ8 testing when celiac disease is strongly suspected despite negative serology, which has high negative predictive value (absence makes celiac disease highly unlikely) 2, 7
- In children under 2 years, combining tTG-IgA with IgG and IgA deamidated gliadin peptides is recommended for improved sensitivity 6
- Recent guidelines suggest children with tTG-IgA ≥10× upper limit of normal, positive EMA-IgA, and positive HLA may avoid biopsy 8, 9
High-Risk Groups to Consider Testing
- Patients with unexplained iron deficiency anemia should be considered for testing 3, 5
- Patients with premature onset of osteoporosis should be considered for testing 5
- Patients with Down syndrome should be considered for testing 3, 5
- Patients with unexplained liver transaminase elevations should be considered for testing 5
- Patients with type 1 diabetes mellitus should be considered for testing 3, 5
- First-degree relatives of patients with celiac disease should be considered for testing 3, 5
- Patients with autoimmune thyroid disease should be considered for testing 5