The following combinations of antibody test and biopsy (total IgA in the normal range) are conceivable:
- TTG-IgA or EmA-IgA antibodies elevated, biopsy with villous atrophy: celiac disease confirmed.
- TTG-IgA or EmA-IgA antibodies in the normal range, biopsy with villous atrophy: unclear situation, clarify other possibilities for villous atrophy, celiac disease possible
- TTG IgA or EmA IgA antibodies elevated, biopsy WITHOUT villous atrophy: potential celiac disease or error in sample examination or antibody determination. In consultation with the patient / depending on the symptoms, a gluten-free diet should not yet be started, if possible. Further monitoring necessary
In case of IgA deficiency:
TTG-IgA or EmA-IgA antibodies in the norm -> determination of IgG antibodies against tissue transglutaminase or deamidated gliadin peptides (DGP-IgG)
If IgG antibodies are elevated: biopsy. If villous atrophy: celiac disease confirmed, if no villous atrophy: consider other cause or continue gluten-containing diet and follow up.
If IgG antibodies are normal: celiac disease unlikely, consider other cause of symptoms.
In children and adolescents up to 18 years of age, the diagnosis can in many cases be made without performing a small intestine biopsy during a gastrointestinal endoscopy. To do so, all of the following criteria must be met:
- tTG-IgA at least 10 times above the normal limit (example: limit is 7 U/ml, laboratory result is 91 U/ml: the value is thus 13 times above the normal value).
- Collection of a second blood sample and determination of the autoantibodies endomysium (EMA-IgA)
If EMA-IgA is also positive: start of gluten-free diet, celiac disease confirmed.