Celiac Disease Screening and Diagnosis
There are several ways to know if you should get tested for celiac disease. The first, most obvious one would be if you are showing symptoms of the disease. In addition to this, another reason for getting tested would be if you have a first relative who has celiac disease. This is because celiac disease is hereditary and those who have parents, siblings, or children with the disease are at a higher risk of having the antibodies. Finally, the last reason some should get tested is if they have other autoimmune disorders as it has been shown that they can be linked.
If you feel like you fit into one of these categories. It is important to know what they are testing for when they screen you for celiac disease. The first way that doctors will go about testing for celiac disease is through a blood test. Those who have celiac disease and eat gluten have higher levels of specific antibodies in their blood. These antibodies are produced by the immune system due to the fact that it sees gluten as a harm. However, prior to being tested, it is important to remain on a gluten-containing diet so that these antibodies are present otherwise the blood test will not be accurate. It is important to realize that a positive result does not ensure that you have celiac disease, but they do show potential for having it. Therefore, after obtaining a positive result in any of these tests, further screening must be performed.
The most common blood test used to test for celiac disease is the Tissue Transglutaminase IgA and IgA antibody test. These blood screenings check to see if your body is producing the antibodies as an effect of the ingestion of gluten. While this test is accurate for 98% of patients with celiac disease and 95% of people without celiac disease, there is still the chance of a negative test result even if you have celiac disease. In addition to this, those who have other autoimmune disorders are at risk of having a false positive test result.
In cases where there is a potential of a false positive or negative, other antibody tests can be used. These include a total serum IgA test which checks for IgA deficiency, a symptom of celiac disease, a deaminated gliadin peptide test which is used in those who test as a false negative, and a IgA endomysial antibody test which is not as accurate because some people who have celiac disease do not produce positive results anyways.
In addition to these blood tests, your doctor may want to do genetic testing. In this genetic testing, doctors look for HLA DQ2 and DQ8 genes. People who have celiac disease have one or both of these. Positive results of this testing mean that you carry the genes that may cause you to develop celiac disease some time in your life. However, you may not. Negative test results, in which neither of the genes is present, exclude the possibility of developing celiac disease. Therefore, genetic testing cannot be used as a diagnosis for if you have celiac disease or not but more so as a way to know if you will ever have it.
Once one of these tests show that you have the possibility of having celiac disease, your doctor will need to do an endoscopy. From this endoscopy, your doctor will be able to see any inflammation or damage done to your small intestine by looking at the state of your villi. They will also take a biopsy of the small intestine to be used to diagnose if you have celiac disease or not.
An important aspect of celiac screening is to acknowledge negative results. Personally, I have found this side of the spectrum somewhat frustrating. Acknowledging negative results means that if you are still expressing symptoms, especially if you have a first relative with the disease, you need to talk to your doctor about further testing. Further testing would include an endoscopy with a biopsy, even though bloodwork comes back negative. It is also important to remember that you can develop celiac disease at any age. So even though you got tested before and it came back negative, if a few years later you feel symptoms then getting tested again may show different results. Celiac disease is a condition that you want to catch early on before it does a lot of damage and to do this you need to pay attention to what your body is telling you.