Testing for celiac disease: IgA Blood Test
Updated: Nov 8, 2022
Many community members were asking about their blood tests results. They wondered if the blood test results are accurate and some of them asked if it is normal to get blood tests after an endoscopy positive for celiac disease.
We need to clarify that there are two types of blood tests in celiac disease diagnosis: immunoglobulin and genetic. The blood tests asked in the community were concerning the immunoglobulin A (IgA) blood test, which is the most common first step in celiac disease diagnosis.
The human body has many types of antibodies. One of the types of antibody in our blood is the IgA. There's a subgroup of the IgA antibodies associated with celiac disease, namely TTG-IGA. More specifically, the TG2-IgA antibodies (Husby and colleagues, 2019).
Source: https://doi.org/10.1053/j.gastro.2018.12.010
After compiling the data of 22 studies, Hill (2005) determined that the accuracy of TTG-IgA tests for correctly diagnosing people with celiac disease is between 77 and 100% of the times. This blood test is very helpful to diagnose celiac disease, particularly in children.
Source: https://doi.org/10.1053/j.gastro.2005.02.012
However, most of immunoglobulin blood tests are based on detecting IgA antibodies. Thereby, these tests may not allow to diagnose individuals who have both celiac disease and IgA deficiency.
Before the blood test, you should continue eating gluten daily to make sure your body produces the antibodies that will later be detected in your blood sample.
Before the endoscopy, you should continue eating gluten daily to have evidence of an autoimmune attack in your intestines.
After being diagnosed with celiac disease, start your gluten-free diet and do not forget to have follow-up tests.
If symptoms continue in spite of a gluten-free diet and normal levels of TTG-IgA, a second endoscopy is advised to check the intestinal villi condition.
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