Coeliac disease – Diagnostics – Overview of Information and Clinical Research

Understanding when and how to diagnose coeliac disease is essential for protecting long-term health and preventing serious complications. Many people live with the condition for years without knowing it, as symptoms can vary widely or even go unnoticed. Early and accurate diagnosis helps people start treatment promptly and avoid damage to their intestines and other parts of the body.

Introduction: Who Should Seek Diagnostic Testing

Coeliac disease is a condition where the body’s immune system reacts abnormally when gluten is consumed. Gluten is a protein found naturally in wheat, barley, and rye. When someone with coeliac disease eats gluten, their immune system attacks the lining of the small intestine, causing damage and inflammation. Over time, this prevents the body from properly absorbing nutrients from food, which can lead to many health problems.^[1]^[2]

You should consider getting tested for coeliac disease if you experience certain symptoms or belong to specific risk groups. People who have digestive issues such as diarrhea, stomach pain, bloating, gas, or constipation should speak with their doctor about testing. However, not everyone with coeliac disease has obvious digestive symptoms. Some people experience tiredness, unexplained weight loss, anemia, or skin rashes instead. Children may show delayed growth or development. In fact, some people have no noticeable symptoms at all, even though damage is happening inside their bodies.^[2]^[4]

Certain groups of people have a higher chance of developing coeliac disease and should be tested even if they feel healthy. If you have a close family member with coeliac disease—such as a parent, sibling, or child—you are at increased risk and should be screened. People with other autoimmune conditions like type 1 diabetes or autoimmune thyroid disease are also more likely to have coeliac disease. Additionally, individuals with Down syndrome, Turner syndrome, or Williams syndrome face higher risk and should undergo testing.^[4]^[5]

⚠️ Important

It is crucial to continue eating foods with gluten before getting tested for coeliac disease. If you stop eating gluten before the tests, the results may appear normal even if you have the condition. This is because your body needs to be reacting to gluten for the tests to detect the problem. Only eliminate gluten from your diet after consulting with your doctor and completing all necessary tests.^[8]

Classic Diagnostic Methods

Diagnosing coeliac disease involves several steps, and doctors use a combination of tests to confirm whether someone has the condition. The process typically begins with blood tests and may progress to more detailed examinations of the intestine.^[6]

Blood Tests

The first step in diagnosing coeliac disease is usually a blood test. These tests look for specific antibodies that the immune system produces when someone with coeliac disease eats gluten. Antibodies are proteins made by the immune system to fight what it perceives as threats. In coeliac disease, the body mistakenly creates antibodies against its own tissues when gluten is present.^[8]

The most common blood test checks for elevated levels of certain antibody proteins. When these antibody levels are higher than normal, it indicates an immune reaction to gluten. However, blood tests alone cannot definitively diagnose coeliac disease—they suggest that further investigation is needed. Some people with coeliac disease may have negative blood tests, which means the antibodies don’t show up even though they have the condition. This happens about 10 percent of the time.^[7]

Doctors may also use genetic testing to look for specific genes called HLA-DQ2 and HLA-DQ8. Almost everyone with coeliac disease has one of these genetic changes. However, having these genes doesn’t mean you will definitely develop the disease—many people carry these genes but never get coeliac disease. Genetic testing is mainly useful for ruling out coeliac disease. If you don’t have these genes, it’s extremely unlikely you have the condition.^[8]^[13]

Endoscopy and Intestinal Biopsy

If blood tests suggest coeliac disease, the next step is usually an endoscopy. This procedure allows doctors to look directly at the inside of the small intestine and take small tissue samples for examination. An endoscopy uses a thin, flexible tube with a tiny camera on the end, called an endoscope. The doctor gently inserts this tube through your mouth, down your throat, and into your small intestine.^[8]

During the endoscopy, the doctor can see the lining of your small intestine on a screen. They also take a small piece of tissue, called a biopsy, from the intestinal lining. This tissue is then examined under a microscope in a laboratory. The normal lining of the small intestine is covered with tiny, finger-like projections called villi that help absorb nutrients. In people with coeliac disease, these villi become damaged, flattened, or destroyed. This damage is called villous atrophy. The biopsy can reveal this damage and confirm the diagnosis.^[15]

Sometimes doctors use a capsule endoscopy instead of the traditional procedure. For this test, you swallow a small capsule about the size of a large vitamin pill. The capsule contains a camera that takes pictures as it travels through your digestive system. The images are sent to a recorder that you wear on your belt. This method allows doctors to see the entire small intestine, not just the first part.^[8]

Physical Examination

Before ordering tests, your doctor will take your medical and family history and perform a physical exam. They will ask about your symptoms, what foods you eat, and whether anyone in your family has coeliac disease or other autoimmune conditions. The physical exam may reveal signs that suggest coeliac disease, such as abdominal swelling, paleness from anemia, or a specific type of itchy rash called dermatitis herpetiformis. This rash appears as clusters of bumps or blisters on the elbows, knees, buttocks, and scalp and affects about 15 percent of people with coeliac disease.^[6]^[4]

Distinguishing from Other Conditions

Coeliac disease can be confused with other digestive conditions because the symptoms overlap. Doctors need to make sure your symptoms aren’t caused by something else, such as irritable bowel syndrome, inflammatory bowel disease, intestinal parasites, or cystic fibrosis. They may also rule out gluten sensitivity and wheat allergy, which are different from coeliac disease.^[7]

Gluten sensitivity causes similar symptoms to coeliac disease, such as abdominal pain and tiredness, but it does not damage the small intestine. A wheat allergy is a type of food allergy where the immune system reacts to wheat, but it causes different symptoms like itchy eyes, difficulty breathing, or skin reactions. Unlike coeliac disease, wheat allergy does not cause long-term damage to the intestine.^[3]^[6]

⚠️ Important

Routine testing for coeliac disease is not done in many countries. Testing is usually only recommended for people who have symptoms or are at increased risk. If you think you might have coeliac disease, talk to your doctor about whether testing is right for you. Don’t start a gluten-free diet on your own before being tested, as this can make diagnosis difficult or impossible.^[5]

Diagnostics for Clinical Trial Qualification

When researchers conduct clinical trials to test new treatments for coeliac disease, they need to make sure that participants actually have the condition. The diagnostic tests used to qualify patients for clinical trials are similar to those used in regular medical practice, but they may be more detailed or strict. This ensures that the study results are accurate and that only people who will benefit from the experimental treatment are included.^[1]

To participate in a clinical trial for coeliac disease, you typically need to have a confirmed diagnosis. This usually means you have had positive blood tests showing elevated antibodies and a biopsy of your small intestine showing damage to the villi. Some trials may require genetic testing to confirm you have the HLA-DQ2 or HLA-DQ8 genes associated with coeliac disease.^[8]^[13]

Clinical trials may also have specific requirements about how recently you were diagnosed or how severe your intestinal damage is. Some trials are looking for people who still have symptoms despite following a gluten-free diet, while others may want participants who are newly diagnosed and haven’t started treatment yet. Researchers might exclude people who have other serious health conditions or who are taking certain medications that could interfere with the study results.^[14]

Before enrolling in a trial, you will undergo a thorough medical evaluation. This may include repeating some diagnostic tests even if you were previously diagnosed. The research team wants to have up-to-date information about your condition at the start of the study. You may also need additional tests that aren’t part of routine care, such as more detailed measurements of intestinal damage or assessments of how well you’re absorbing nutrients.^[11]

Prognosis and Survival Rate

Prognosis

For most people with coeliac disease, the outlook is very good when the condition is properly managed with a strict gluten-free diet. Following this diet allows the small intestine to heal, and symptoms typically improve within days to weeks. Complete healing of the digestive system may take up to a few years, but most people experience significant relief much sooner. When people stick to a gluten-free diet, they can lead completely normal, healthy lives.^[9]^[10]

However, if coeliac disease is left untreated or if people continue to eat gluten, serious complications can develop. Long-term damage from untreated coeliac disease can lead to malnutrition, which means the body doesn’t get the vitamins, minerals, and other nutrients it needs. This can cause a range of problems including weakening of the bones (osteoporosis), iron deficiency anemia, vitamin deficiencies, infertility, and problems during pregnancy such as low birth weight babies. In children, untreated coeliac disease can cause delayed growth and development.^[4]^[5]

Some people continue to have symptoms even when following a gluten-free diet, often because they are accidentally consuming small amounts of gluten from cross-contamination or hidden sources. Persistent symptoms can also occur if the intestinal damage is severe or if someone has what’s called refractory coeliac disease, where the intestine doesn’t respond to a gluten-free diet. These situations require close monitoring and specialized medical care.^[14]

Survival rate

With proper diagnosis and treatment through a lifelong gluten-free diet, people with coeliac disease have a normal life expectancy. The condition itself is not fatal when managed correctly. However, untreated coeliac disease can increase the risk of certain serious complications. There is a small but real increased risk of developing certain types of cancer, particularly lymphoma of the small bowel, if the disease remains untreated over many years. This risk decreases significantly when people follow a gluten-free diet and their intestines heal.^[5]^[15]

The key to a good prognosis is early diagnosis and strict adherence to a gluten-free diet. People diagnosed with coeliac disease should have regular follow-up appointments with their healthcare provider to monitor their condition, ensure their symptoms are improving, and check for any complications. With modern awareness, widely available gluten-free foods, and proper medical support, the vast majority of people with coeliac disease can live full, healthy lives without any reduction in life expectancy.^[10]

#1 Clinical Trials Search in Europe