Celiac disease is a serious autoimmune condition where the ingestion of gluten leads to damage in the small intestine. If you suspect that gluten—a protein found in wheat, barley, and rye—is causing health issues, getting a formal celiac disease test is the only way to confirm a diagnosis. Understanding the testing process is essential for anyone experiencing chronic digestive issues or unexplained fatigue.
At SearchAndHelp.com, we aim to simplify complex medical topics so you can take charge of your health. This guide will walk you through the different types of tests available, the preparation required, and what to expect during the diagnostic process. By following these steps, you can ensure your results are as accurate as possible.
Why You Must Not Start a Gluten-Free Diet Yet
The most critical piece of advice for anyone seeking a celiac disease test is to continue eating gluten until all testing is complete. This is often called the “gluten challenge.” If you stop eating gluten before your blood test or biopsy, your body may stop producing the antibodies the test is designed to detect.
When you remove gluten from your diet, your small intestine begins to heal. While this is good for your health, it can lead to a “false negative” result on your tests. Doctors typically recommend eating at least one or two servings of gluten daily for several weeks leading up to the screening.
Step 1: The Celiac Disease Blood Test
The first step in the diagnostic process is usually a simple blood test known as a serology test. This test looks for specific antibodies in your blood that indicate an immune reaction to gluten. The most common test is the tTG-IgA (Tissue Transglutaminase IgA) test.
If the tTG-IgA test comes back positive, it suggests that you likely have celiac disease. However, blood tests are not 100% definitive. Some people may have a positive blood test but a normal intestine, while others with the disease may occasionally test negative if they have an IgA deficiency.
Other Blood Tests Your Doctor Might Order
- Total Serum IgA: This is used to check if you have an IgA deficiency, which could make other tests unreliable.
- Deamidated Gliadin Peptide (DGP) Antibodies: These are often used if a person has an IgA deficiency or if the patient is a very young child.
- EMA (Endomysial Antibody): This is a highly specific test usually reserved for difficult-to-diagnose cases.
Step 2: The Small Intestine Biopsy
If your blood tests indicate a high probability of celiac disease, the next step is a biopsy of the small intestine. This is considered the “gold standard” for diagnosis. A gastroenterologist performs this procedure during an upper endoscopy.
During the endoscopy, a thin, flexible tube with a camera is passed through your mouth and into your small intestine. The doctor will take several small tissue samples (biopsies) from the lining of the intestine. These samples are then examined under a microscope to look for damage to the villi, which are tiny, finger-like projections that help absorb nutrients.
In a person with celiac disease, these villi become flattened or destroyed. This damage confirms the diagnosis and helps the doctor determine the severity of the condition.
Genetic Testing for Celiac Disease
Genetic testing is a different approach that looks for specific markers on your DNA. Specifically, it looks for the HLA-DQ2 and HLA-DQ8 genes. Almost everyone with celiac disease carries one of these two gene variants.
It is important to note that having these genes does not mean you have the disease; about 30% of the general population carries them, but only a small fraction develops celiac disease. Genetic testing is most useful for ruling out the disease. If you do not have these genes, it is virtually impossible for you to have celiac disease.
Genetic tests are often used when blood test results are unclear or when a person has already started a gluten-free diet and does not wish to perform a gluten challenge.
Who Should Be Tested?
Celiac disease can present with a wide variety of symptoms, some of which do not involve digestion at all. You should talk to your doctor about a celiac disease test if you experience any of the following:
- Digestive Issues: Chronic diarrhea, constipation, gas, bloating, or abdominal pain.
- Nutrient Deficiencies: Unexplained iron-deficiency anemia or vitamin B12 deficiency.
- Weight Changes: Unexplained weight loss or, in children, a failure to thrive or meet growth milestones.
- Skin and Bone Issues: An itchy, blistering skin rash (dermatitis herpetiformis) or early-onset osteoporosis.
- Neurological Symptoms: Frequent migraines, “brain fog,” or numbness and tingling in the hands and feet.
Additionally, because celiac disease is hereditary, first-degree relatives (parents, siblings, or children) of someone diagnosed with the condition should be screened, even if they have no symptoms.
How to Prepare for Your Appointment
To get the most out of your doctor’s visit, it helps to be prepared. Start by keeping a symptom diary for two weeks, noting what you eat and how you feel afterward. This provides your doctor with clear evidence of your concerns.
When you meet with your healthcare provider, be sure to mention any family history of autoimmune diseases, such as Type 1 diabetes or thyroid disease, as these are often linked to celiac disease. Ask specifically for a “Celiac Serology Panel” to ensure the correct blood tests are ordered.
Understanding Your Results
Once your tests are complete, your doctor will review the findings with you. A positive result on both the blood test and the biopsy confirms celiac disease. At this point, the only treatment is a strict, lifelong gluten-free diet.
A negative result on all tests usually means you do not have celiac disease. However, if you still feel poorly when eating gluten, you may have Non-Celiac Gluten Sensitivity (NCGS). NCGS causes similar symptoms but does not cause the same intestinal damage found in celiac disease.
If your results are inconclusive, your doctor might suggest further genetic testing or a repeat of the biopsy after a longer gluten challenge. Never self-diagnose; always rely on medical data to make changes to your health regimen.
Summary and Next Steps
Getting a celiac disease test is a straightforward process involving blood work and, if necessary, an intestinal biopsy. The most important rule to remember is to keep gluten in your diet until the testing is finalized to ensure accuracy. Identifying the cause of your symptoms is the first step toward healing and regaining your energy.
If you receive a diagnosis, your doctor will likely refer you to a registered dietitian who specializes in gluten-free living. For more information on managing your health and understanding dietary needs, explore our other helpful articles on SearchAndHelp.com.