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Diagnosis of Celiac disease

Coeliac disease is an autoimmune disease where the lining of the small intestine is damaged by exposure to gluten (a protein found in grains such as wheat, rye, barley and oats) in genetically predisposed children and adults. The reaction to gluten causes inflammation and atrophy of intestinal lining, which can lead to malabsorption of nutrients and related health issues.

The diagnosis of Celiac disease is classically based on a combination of findings from a patient’s clinical history, serologic testing and duodenal biopsies.

SEROLOGY TEST:

Serologic tests are for screening purposes and do not confirm the diagnosis of coeliac disease. Serologic tests for celiac disease include anti-transglutaminase IgA & IgG antibody, anti-endomysium IgA antibody, and Deamidated Gliadin Peptide IgA & IgG antibodies.  The serologic tests that check for IgA antibodies are more sensitive for celiac disease than the tests for IgG antibodies. However, in people who have IgA deficiency, IgG tests may be useful. For accurate diagnostic test results, a patient must be eating a diet that contains gluten. False-positive results in serologic tests are uncommon but can occur. 

Anti-Transglutaminase IgA (tTG-IgA): The tTG IgA antibody is the preferred and cost effective test for screening patients of all ages (over the age of 2 years). The sensitivity of tTG IgA antibody is lower in children younger than 2 years of age. tTG IgA antibody can also be used to monitor the condition and to help evaluate the effectiveness of treatment.

Total serum Immunoglobulin A (IgA) test is used to check for IgA deficiency, a condition commonly associated with celiac disease (2%–3%, compared with 0.2% in the general population), that can cause a false negative tTG-IgA. tTG - IgG test may be used as an alternative test in people who have a deficiency of IgA.

Anti-endomysial antibodies (EMA) IgA : The EMA test is the most specific test for celiac disease, although it is not as sensitive as the tTG-IgA test. The EMA-IgA test is an immunofluorescent assay (IFA) that is more expensive and time-consuming to perform than the tTG-IgA test. 

Deamidated gliadin peptide antibodies (anti-DGP), IgA & IgG: This is the latest generation serologic test. DGP IgA antibody test is less sensitive and specific than the tTG-IgA test while DGP IgG antibody is slightly more sensitive than the tTG -IgG antibody. DGP IgG testing along with anti-tTG IgG is recommended by the American College of Gastroenterology for people who have low IgA or IgA deficiency.  The sensitivity of tTG  IgA and EMA IgA antibody tests is lower in children younger than 2 years of age. Therefore, testing with the DGP IgA/IgG antibody, along with the tTG IgA/IgG antibody, is recommended in this age group.

All positive and indeterminate serology tests for celiac disease are followed by an intestinal biopsy. A biopsy is used to make a definitive diagnosis of celiac disease.

Genetic testing for human leukocyte antigens (HLA-DQ2 and HLA-DQ8) can be used to rule out celiac disease.

Who should get screened?

1. Any person experiencing symptoms of celiac disease. 

2. First-degree relatives of patient of celiac disease.

3. Any person with an associated autoimmune disorder especially type 1 diabetes mellitus, autoimmune thyroid disease, autoimmune liver disease, and or other conditions like Down syndrome, Turner syndrome, Williams syndrome, and selective immunoglobulin A (IgA) deficiency.


Dr Prashant Goyal



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