Celiac Disease and Elevated Gliadin IgA

Primary Cause: Celiac Disease

Elevated gliadin IgA antibodies are primarily caused by celiac disease, an autoimmune disorder triggered by gluten ingestion in genetically susceptible individuals, though they can also be elevated in other small intestinal diseases, particularly active Crohn's disease 1, 2
Celiac disease is the most specific and common cause of elevated gliadin IgA antibodies, occurring when the immune system reacts to gliadin (a gluten protein found in wheat, barley, and rye) 1, 2

Screen for celiac disease by measuring IgA tissue transglutaminase (tTG) antibodies with documentation of normal total serum IgA levels, as this is the preferred first-line test with 90-96% sensitivity 1, 2
If IgA deficient, measure IgG to tTG and deamidated gliadin antibodies instead, as IgA deficiency causes falsely negative IgA-based tests 1, 2
The specificity of gliadin antibodies is lower than tTG or endomysial antibodies, which is why current guidelines prioritize tTG-IgA as the primary screening test rather than gliadin antibodies alone 1, 2

Type 1 diabetes occurs in 1-16% of celiac patients versus 0.3-1% in general population 1, 2
Autoimmune thyroid disease occurs in 17-30% of type 1 diabetes patients who also have celiac disease 2, 3
Addison's disease, autoimmune hepatitis, and other autoimmune conditions occur more frequently with celiac disease 1, 4

Never interpret gliadin IgA results without measuring total IgA levels, as selective IgA deficiency causes falsely negative IgA-based tests 1, 2
Confirm elevated gliadin IgA with tTG-IgA and total IgA measurement 1, 2

Proceed to upper endoscopy with at least 6 duodenal biopsies if antibodies positive 1, 2
Screen for associated autoimmune conditions (thyroid function, fasting glucose/HbA1c) 1, 2, 3

The American Gastroenterological Association recommends that patients with elevated tTG-IgA levels undergo confirmatory testing, including endomysial antibody (EMA) testing, which has excellent specificity (99.6% in adults) 5, 6
The combination of positive tTG-IgA and positive EMA has virtually 100% positive predictive value for celiac disease 5
Patients with low to moderately positive tTG-IgA levels should be interpreted in the context of symptoms, and if EMA is negative, repeat testing every 6-12 months while maintaining gluten intake is appropriate 7, 5

Upper endoscopy with duodenal biopsy remains the gold standard for diagnosis and should be performed before initiating any dietary changes, with at least 6 biopsy specimens from the second part of the duodenum or beyond for Marsh classification 5, 6
The biopsy specimens should be evaluated by a pathologist with gastroenterology expertise, as poorly oriented mucosa can lead to misinterpretation 5

The American College of Gastroenterology recommends that patients with confirmed celiac disease initiate a strict gluten-free diet immediately after biopsy confirmation, and refer to a registered dietitian experienced in managing celiac disease for comprehensive dietary education 5, 7, 8
Monitor tTG-IgA levels at 6 months after starting gluten-free diet, at 12 months, and annually thereafter, as persistently elevated tTG-IgA despite treatment suggests ongoing gluten exposure or poor dietary compliance 5, 8, 6

Screen for associated autoimmune conditions, including type 1 diabetes and autoimmune thyroid disease, and evaluate for nutritional deficiencies with CBC and iron studies, as celiac disease is present in 2-6% of patients with unexplained iron deficiency 5

If gliadin IgA is elevated, measure tissue transglutaminase (tTG) IgA with total serum IgA levels as the preferred confirmatory test, which has 90-96% sensitivity and superior specificity compared to gliadin antibodies alone, as recommended by the American Academy of Allergy, Asthma, and Immunology 9
The American Gastroenterological Association suggests that if IgA deficient, measure IgG-based tests instead, as IgA deficiency causes falsely negative IgA-based tests, with a prevalence of 1-3% in celiac patients 9

Proceed to upper endoscopy with at least 6 duodenal biopsies if tTG-IgA is positive, as biopsy remains the gold standard for diagnosis, according to the American College of Gastroenterology 9
Screen for associated conditions, including thyroid function tests, fasting glucose/HbA1c for type 1 diabetes, CBC and iron studies for anemia, as recommended by the Endocrine Society 9