Celiac Disease Testing By Jane Anderson - Reviewed by a board-certified physician. Updated July 13, 2016 You may have one (or more) different reasons to pursue testing for celiac disease. Perhaps you suffer from celiac disease symptoms, which can range from diarrhea and weight loss to neurological problems and weight gain.You may have a close family member who was diagnosed with celiac disease and have learned that medical guidelines recommend celiac disease testing for relatives, since the condition runs in families. Or, you may suffer from one or more related conditions, such as thyroid problems or type 1 diabetes. Studies have shown that celiac disease is more common in people with these conditions.Regardless of your reasons for wanting to consider a celiac disease diagnosis, testing for celiac disease is a fairly lengthy process. In most cases, you'll first have blood tests done, and then ultimately, will have a procedure known as an endoscopy, in which doctors look directly at your small intestine. Article Do You Have IBS, or Do You Really Have Some Sort of Issue with Gluten? List Have Celiac Disease? Here's What Those Marsh Score Numbers Mean Note: You must be eating gluten for celiac disease testing to be accurate. If you are being tested for celiac disease, do not go gluten-free until all your testing is completed.In the best-case scenario, you'll have your answer within a few days or a week, but the diagnostic process can take much longer in some areas, especially where gastroenterologists (specialists in the digestive system) are in short supply. Here's what to expect from every stage of the process.Celiac Disease TestsCeliac disease is a condition that involves your body's reaction to the protein gluten, which is found in the common grains wheat, barley, and rye. Tests for celiac disease look for this reaction to gluten. In people with celiac disease, eating foods that contain gluten (which occurs at almost every meal on a standard diet) causes what's called an autoimmune reaction, in which your body's disease-fighting white blood cells mistakenly attack some of your own tissue.Different autoimmune diseases cause different types of damage in the body. In the case of celiac disease, the white blood cells attack the lining of your small intestine, causing what's known as villous atrophy. Ultimately, this can destroy the lining of your intestine, meaning you're unable to absorb nutrients from your food.Because the tests for celiac disease are looking specifically for signs of this small intestine damage, you must be eating gluten for the tests to be accurate. If you're not eating gluten-containing foods—or not eating enough of them—it's possible for the testing to come up negative, even if you actually do have celiac disease. Therefore, you should continue eating a normal diet, with gluten-containing foods several times a day, until all your testing is completed. Article Eating More Gluten at an Early Age May Raise Your Child's Celiac Risk Article Here's Why You Should See Your Doctor Regularly If You Have Celiac Of course, some people do go gluten-free before they decide to be tested for celiac disease. If you've already started following the gluten-free diet, you may want to consider what's called a "gluten challenge," in which you eat a set amount of gluten for some period of time, and then undergo testing for celiac disease. This tactic does carry some risks, though, and may not produce the results you want, so talk to your doctor about the potential risks and benefits.First Step in Celiac Disease Testing: Blood TestsIn most cases, celiac disease blood testing (which can be ordered by your primary care doctor) will be the first step toward a diagnosis. There are five blood tests commonly used to detect celiac disease, although many doctors will only request one or two of the tests.If your body is undergoing an autoimmune reaction to gluten, one or more of these blood tests most likely will come up positive, indicating the need for further testing to see if you truly have celiac disease.However, it is possible for you to have negative blood test results and to still have celiac disease. Some people have a condition known as IgA deficiency that can cause false negative results on some celiac disease blood tests. If you have this (there's yet another blood test that will look for it), you'll need different tests to screen for celiac disease.In a few other cases, the blood test results simply don't reflect the amount of intestinal damage present. This also is known as a "false negative" test result.Therefore, if your blood tests are negative, but your symptoms and family medical history still indicate a strong possibility of celiac disease, you should talk to your physician about further testing.Next Step: Endoscopy and Intestinal BiopsyIf your celiac disease blood tests come back positive—or if they're negative, but you and your physician agree on the need for further testing anyway—your next step is a procedure known as an endoscopy. This usually is performed by a gastroenterologist, one of the many types of doctors who treat celiac disease.In an endoscopy, an instrument with a tiny camera attached is threaded down your throat so your physician can look directly at the lining of your small intestine to see if villous atrophy is present. Article More Women Get Celiac Disease Than Men. Why Does This Happen? Article Even Older People Can Get Celiac Disease. Learn Your Risk In some cases (but not all), the damage from celiac disease can be seen immediately during this procedure.However, to confirm the diagnosis, the surgeon also will use the instrument to take tiny samples of your intestine. Because damage from celiac disease can be patchy, the surgeon should take at least four to six samples. These samples then will be examined under a microscope by a pathologist (a doctor who diagnoses disease by examining body tissue directly) to determine if your intestines are damaged. If the pathologist sees damage, you'll be diagnosed with celiac disease.The final piece to the puzzle is your reaction to the gluten-free diet—if your symptoms begin to improve once you go gluten-free, you've just confirmed your diagnosis.Some medical centers also are using capsule endoscopy, in which you swallow a pill with a tiny camera to screen for celiac disease. This has the benefit of seeing parts of your small intestine that can't be reached by conventional endoscopy instruments. However, capsule endoscopy doesn't allow the surgeon to take samples of your intestine, and may not be as accurate in identifying damage as traditional endoscopy.Just as it's possible to have negative blood tests but a biopsy that shows you have celiac disease, It's also possible to have positive blood tests but a negative biopsy. This is known as "latent celiac disease" or sometimes as "potential celiac disease." If you fall into this category, your doctor likely will recommend regular repeat endoscopies, since many people with latent celiac disease ultimately develop full-blown intestinal damage. You also can discuss the possibility of following the gluten-free diet as a trial, to see if any symptoms clear up.Dermatitis Herpetiformis Diagnosis Means Celiac, TooThere is one way you can obtain a diagnosis of celiac disease without undergoing an endoscopy and intestinal biopsy.If you have an itchy, painful blistering skin rash called dermatitis herpetiformis, plus positive celiac blood tests, you're officially diagnosed with celiac disease as well—no further testing required. That's because studies have shown that nearly everyone with dermatitis herpetiformis—which, like celiac disease, is caused by an autoimmune reaction to gluten—also has intestinal damage from gluten ingestion.However, to obtain a gold-standard diagnosis of dermatitis herpetiformis, you'll need to undergo a skin biopsy. This biopsy looks for deposits of anti-gluten antibodies under your skin.Celiac Disease Genetic Testing Also Plays a RoleIn some cases, your doctor may recommend genetic testing for celiac disease. Celiac disease is linked to two specific genes, which are passed down through families.Genetic tests can't tell you if you actually have celiac disease—for that, you'll need to undergo the blood tests and endoscopy described above. But genetic tests can tell you whether you have one of the genes you generally need to develop celiac disease.If you don't have one of these two main genes, the odds of you having celiac disease are very slim, although some cases of celiac have been documented in people who don't carry either gene.The genetic test for celiac is the one test you can undergo regardless of whether you're currently eating gluten or not—the test looks for the genetic predisposition to the condition, not for antibodies that indicate an active case of celiac disease. Therefore, it might provide you with some information if you've already gone gluten-free due to a bad reaction to gluten-containing foods, but now want to know whether or not you might actually have celiac disease.If you have a positive genetic test for celiac disease, it doesn't mean you definitely have celiac disease—up to 40 percent of the population carries one of those genes, and the vast majority never develop celiac. However, it does mean you possibly can develop the condition. You'll need to discuss with your doctor your next steps if your celiac disease gene test comes back positive, especially if you have a family history of celiac disease.Celiac Disease Diagnosis Means Gluten-Free DietPositive test results for celiac disease on your endoscopy and biopsy means you definitely have the condition, and must follow the gluten-free diet for life. Although this can seem overwhelming at first, you ultimately may find your health improves dramatically and that you don't really mind eating gluten-free. Truthfully, there are many, many foods you can eat when you're gluten-free.Negative testing, meanwhile, doesn't mean you definitely don't have a problem with gluten. You can test negative on celiac blood tests and biopsy and still suffer from problems related to gluten ingestion.Some people who test negative for celiac disease nonetheless still have symptoms that clear up on a gluten-free diet. In some cases, people are being diagnosed with non-celiac gluten sensitivity (sometimes also called gluten intolerance or gluten allergy), a recently recognized and as-yet poorly understood condition. There are no generally accepted tests to determine if you have gluten sensitivity—the only way to know is to give up gluten and see if your symptoms clear up.Finally, if you test negative for celiac disease, that doesn't mean you definitely won't develop it in the future. Studies of close relatives of celiac disease patients (who themselves have a high risk of developing the condition) show that repeated screening over the course of years may be necessary to catch all cases.Therefore, if you have risk factors for celiac disease—"celiac" genes, close family members with the condition, other autoimmune diseases, or even just bad symptoms—you may want to consider setting up a regular testing schedule with your physician. If you catch celiac disease early, you can minimize the damage to your body and potentially ward off complications, such as osteoporosis and malnutrition.Sources:National Digestive Diseases Information Clearinghouse. Celiac Disease. Accessed Jan. 16, 2016.University of Chicago Celiac Disease Center. Antibody Blood Tests. Accessed Jan. 16, 2016.University of Chicago Celiac Disease Center. Genetic Testing. Accessed Jan. 16, 2016.