How Celiac Testing Works
There are several different options to test for celiac disease.
- Blood Testing: A blood test is available that checks for certain antibodies. People with celiac disease who eat gluten produce antibodies in their blood because their immune systems view gluten as a threat. It is important to note that you must be on a gluten-containing diet for antibody blood testing. It is also important to note that these types of tests can also be misleading, as they can come back falsely negative about 10-15% of the time.
- Endoscopy: An endoscopy is when a tube is inserted down your throat so that a practitioner can look at your small intestine for inflammation or damage. They may also take a small biopsy of your intestines. Like blood testing, you must be eating a diet that contains gluten for this test to be accurate. This type of testing is accurate when positive, but missed diagnosis is common. A biopsy finding villous atrophy can also be misleading because other things can cause atrophy beyond gluten, such as parasites, glyphosate, non steroidal anti inflammatories (NSAIDS), proton pump inhibitors (PPIs) used traditionally for heartburn, selective serotonin reuptake inhibitors (SSRIs) used for depression and mood disorders, etc.
- Genetic Testing: Genetic testing is a highly accurate look at your genes to understand whether you have a genetic predisposition to reacting to gluten. Make sure to get a test that measures for all genes linked to gluten sensitivity (HLA-DQ1/HLA-DQ3) and celiac disease (HLA-DQ2/HLA-DQ8). Some tests only check for genes linked to celiac disease.
Should You Get Tested?
You might be wondering if you should get tested for celiac disease at all. Here are some instances in which you should test for celiac disease:
- If you are experiencing symptoms of celiac disease, it is best to get tested to confirm a diagnosis and rule out other potentially complicating factors
- If you know that you have a family history of celiac disease – first-degree relatives of people with celiac disease (parents, siblings and children) have a much greater risk compared to 1 in 100 in the general population
- If you have an associated autoimmune disorder or other condition, especially type 1 diabetes mellitus, autoimmune thyroid disease, autoimmune liver disease, Down syndrome, Turner syndrome, Williams syndrome, or a selective immunoglobulin A (IgA) deficiency. Research continues to link the autoimmune spectrum of diseases to gluten sensitivity.
Some people prefer to use symptom recognition as an alternative to formal testing. The benefits to this are that it does not require gluten consumption prior to testing, and it is also less expensive or invasive than some of the other methods. However, the symptoms of celiac disease and gluten sensitivity can overlap with other conditions and can vary greatly from person to person. This can make a diagnosis challenging. Common symptoms include the following:
- Digestive symptoms such as bloating, gas, diarrhea, or constipation
- Skin issues like rash, eczema, or dermatitis herpetiformis
- Fatigue, brain fog, or difficulty concentrating
- Joint pain, muscle aches, or inflammation
- Headaches or migraines
- Mood changes, depression, or anxiety
- Nutrient deficiencies due to malabsorption
- Irregular menstrual cycles or fertility issues
Despite testing flaws and potential false negatives, the best way to diagnose celiac disease is to test. If your test shows up negative, you may want to try a gluten free diet for a few weeks to see if that helps your symptoms. We also suggest working with an experienced practitioner who can help dig deeper to determine if there are other factors at play, like bacteria or yeast overgrowth, infections, parasites, leaky gut, or other conditions.
Should I Eat Gluten Before Celiac Blood Test?
In order to ensure an accurate result on a blood test or endoscopy, you do need to continue eating gluten. This is because once you have eliminated gluten from your diet, antibodies to gluten will start to decrease in your blood, and your intestine will start to heal. Therefore, if you eliminate gluten from your diet prior to a test, there is a risk of a false negative result on both a blood test and endoscopy.
How Much Gluten Should I Eat Before a Celiac Test?
We know that if you have avoided gluten from your diet for a long time, you may be nervous to reintroduce it for fear of dealing with the many symptoms that can come with gluten consumption. This hesitation is understandable and valid, so always consider your own personal circumstances in deciding when and how to introduce gluten into your diet prior to a test.
The Celiac Disease Center at the University of Chicago recommends eating gluten every day, in an amount equivalent to at least 1 slice of bread, for at least 2 to 3 weeks prior to undergoing biopsy.
However, we understand that this type of approach may result in significant discomfort, so know that gluten in any amount prior to your test will help with the accuracy of the results. Smaller or more infrequent servings may work better for your own personal circumstances. In addition, you can consider the quality of the gluten that you choose to consume. Something like organic sourdough may cause less discomfort and have fewer other side effects than a refined and processed form of gluten.
It is best to perform your testing and pre-testing gluten consumption alongside a practitioner who is experienced in working with those with celiac disease. A gluten challenge is not recommended before the age of 5, during puberty, or during pregnancy, as the consumption of gluten can affect nutrient absorption and lead to deficiencies.
There are a number of different ways to test for celiac disease. Both blood testing and endoscopy can yield false negative results and require that you eat gluten before testing in order to increase the chance of an accurate result. As an alternative, genetic testing is available to test for the genes that predispose you to celiac disease. Genetic testing is non-invasive and does not require that you eat gluten prior to testing.