Screening and Diagnosis of Celiac Disease
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Screening
The first step of the screening process for celiac disease is a genetic test. This can be a blood, saliva, or cheek swab test, that looks to see if the genes necessary for celiac disease to develop are present in the individual's body. Individual's with first-degree relatives who had the disease have been shown to be likely to develop it as well, so this test is a good starting point (University of Chicago Celiac Disease Center).
The next step in the screening process is a blood test. This simple blood test is called a tTG-IgA test, short for Tissue Transglutaminase Antibodies, and it will most likely be positive if you have celiac disease. However, it is crucial that you are on a gluten-containing diet at the time of the test, because otherwise, the test will be inaccurate. There is a chance that your test results may reflect a false positive if you have autoimmune diseases such as chronic liver disease, type 1 diabetes, rheumatoid arthritis, and heart failure (Celiac Disease Foundation).
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Other antibody tests include an EMA test (IgA Endomysial antibody test), which is still effective, but not as sensitive as the tTG-IgA test, because 5-10% of people who have celiac disease will have a negative result on this test. A total serum IgA test can be used to check for an IgA deficiency, which is a condition that is relatively harmless that is associated with celiac disease. Finally, a deaminated gliadin peptide test can be given to test people for celiac disease who have an IgA deficiency (Celiac Disease Foundation).
Diagnosis
An intestinal biopsy can be performed to test for celiac disease, in order to confirm the diagnosis suggested by the blood test. An endoscope is used in this process, which is a long skinny tube inserted through the mouth, all the way down to the intestines of the patient. The doctor will take a sample of the small intestine's lining, and observe to see if damage to the villi (projections on in the inner surface of the lining, responsible for nutrient absorption) has occurred (National Digestive Diseases Information Clearinghouse).
The biopsy procedure is usually an outpatient one. Sedatives and local anesthetics are used, and the process takes about 30 minutes total (Celiac Disease Foundation). The patient will be assigned a Marsh classification which will explain the severity of the intestinal damage. Stage 0 is when the internal mucosa of the lining of the small intestine is normal, and celiac disease is extremely unlikely. This stage is also called the "pre-infiltrative stage". Stage 1 is when the surface cells of the inside of the small intestine are being infiltrated by lymphocytes (a white blood cell that is part of the body's immune system). Stage 3 shows a larger amount of lymphocytes, and a lining of the small intestine that is shrinking and flattening out. Stage 4 is when the the villi on the inside of the small intestine are completely flattened out, rendering them relatively ineffective (About.com).
Screening - Celiac Disease Foundation. (n.d.). Celiac
Disease Foundation. Retrieved June 3, 2014, from http://celiac.org/celiac-disease/diagnosing-celiac-disease/screening/http://celiac.org/celiac-disease/diagnosing-celiac-disease/screening/
National Digestive Diseases Information Clearinghouse
(NDDIC). (n.d.). Celiac Disease. Retrieved June 3, 2014, from http://digestive.niddk.nih.gov/ddiseases/pubs/celiac/#diagnosis
Celiac Disease Screening – Univeristy of Chicago Celiac
Disease Center. (n.d.). . Retrieved June 3, 2014, from http://www.cureceliacdisease.org/living-with-celiac/guide/screening
Celiac Disease Marsh Stage - Celiac Disease Marsh Score.
(n.d.). About.com Celiac Disease & Gluten Sensitivity. Retrieved
June 3, 2014, from http://celiacdisease.about.com/od/diagnosingceliacdisease/ss/MarshScore.htm
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