Celiac disease is confirmed through blood tests that measure specific antibodies, usually followed by a small intestine biopsy. But recognizing that you might have it in the first place is the harder part, because symptoms range from obvious digestive problems to subtle issues like chronic fatigue or unexplained anemia. Many people live with celiac disease for years before getting a diagnosis, partly because the symptoms overlap with so many other conditions.
Symptoms That Should Raise Suspicion
The “classic” version of celiac disease looks like what most people expect: diarrhea, weight loss, bloating, and pale or foul-smelling stools that signal your body isn’t absorbing nutrients properly. Children with classic celiac disease often have abdominal pain, chronic diarrhea, and poor growth. If you or your child has this pattern, celiac is usually on the shortlist of things your doctor considers.
But most adults don’t present this way. Non-classical celiac disease can show up as iron-deficiency anemia that doesn’t respond to supplements, chronic migraines, tingling or numbness in your hands and feet, unexplained elevated liver enzymes, reduced bone density, or even depression and anxiety. Some people develop an intensely itchy, blistering skin rash called dermatitis herpetiformis, which is so closely linked to celiac disease that it’s sometimes considered celiac of the skin. Women may notice late first periods, early menopause, or unexplained infertility. Dental enamel defects and chronic vitamin deficiencies (particularly folic acid, B12, and vitamin D) are other clues.
Then there’s silent celiac disease. Some people have no noticeable symptoms at all, yet their immune system is still damaging their small intestine every time they eat gluten. Even trace amounts of gluten cause intestinal harm in people with celiac disease, whether or not they feel it. This is why screening matters for people with risk factors like a first-degree relative with the condition.
The First Step: Blood Tests
Diagnosis starts with a blood test called the tissue transglutaminase IgA test (tTG-IgA). This measures antibodies your immune system produces in response to gluten. Both the tTG-IgA test and a related test called the endomysial antibody test (EMA-IgA) have sensitivity and specificity above 95% in most studies, meaning they catch the vast majority of true cases and rarely flag someone who doesn’t have the disease.
There’s an important catch: you need to be eating gluten regularly for these tests to work. If you’ve already cut gluten from your diet, the antibodies drop and the test can come back falsely negative. Guidelines recommend eating the equivalent of about two slices of wheat bread daily for six to eight weeks before blood testing. If you’re preparing for a biopsy specifically, at least one slice of bread daily for two to three weeks is the minimum. Stopping gluten before testing is one of the most common reasons people get inconclusive results.
A small percentage of people with celiac disease, roughly 2% to 3% based on recent estimates, test negative on antibody tests despite having the condition. This “seronegative” celiac disease is uncommon, but it’s worth knowing about if your blood tests are negative yet your symptoms are persistent and unexplained.
Confirming the Diagnosis: Intestinal Biopsy
A positive blood test typically leads to an upper endoscopy, where a gastroenterologist takes small tissue samples from your small intestine. The procedure itself is quick, usually done under sedation, and most people go home the same day. What the pathologist looks for under the microscope is damage to the tiny finger-like projections (villi) that line your small intestine and absorb nutrients.
The damage is graded on a scale. Early celiac disease may show only an increase in certain immune cells in the intestinal lining without visible structural changes. As the disease progresses, the tissue shows abnormal growth patterns in the deeper layers and increasing levels of villous atrophy, where those finger-like projections flatten out partially, substantially, or completely. A diagnosis is confirmed when this characteristic pattern of damage is present alongside positive antibody results.
For children, European guidelines now allow a diagnosis without biopsy under specific conditions: the tTG-IgA level must be at least 10 times the upper limit of normal, and a second, separate blood sample must test positive for endomysial antibodies. This spares some children from an invasive procedure when the blood work is overwhelmingly clear.
Genetic Testing: Ruling It Out
Genetic testing plays a different role than the other tests. It doesn’t tell you that you have celiac disease. It tells you whether you could develop it. Celiac disease requires the presence of specific gene variants called HLA-DQ2 or HLA-DQ8. About 30% to 40% of the general population carries one or both of these genes, and most of them will never develop celiac disease. So a positive genetic test doesn’t mean much on its own.
Where genetic testing becomes powerful is as a rule-out. If you don’t carry either gene variant, you can essentially cross celiac disease off the list. The negative predictive value is around 98%, meaning a negative result makes celiac disease extremely unlikely. This is particularly useful for family members of someone with celiac disease who want to know their risk, or for people who went gluten-free before getting tested and don’t want to do a prolonged gluten challenge.
Celiac Disease vs. Gluten Sensitivity
If your celiac tests come back negative but you still feel lousy after eating gluten, you may have non-celiac gluten sensitivity. The symptoms can look identical: bloating, fatigue, brain fog, joint pain. The key difference is that non-celiac gluten sensitivity doesn’t cause the same measurable intestinal damage or trigger the same antibody response. There are no reliable biomarkers for it yet, so it’s diagnosed by excluding celiac disease and wheat allergy first, then seeing if symptoms improve on a gluten-free diet and return when gluten is reintroduced.
This distinction matters because celiac disease carries long-term health risks that gluten sensitivity does not. Untreated celiac disease can lead to osteoporosis, severe nutritional deficiencies, and in rare cases, a condition called refractory celiac disease where the intestinal damage persists even on a strict gluten-free diet and may require aggressive treatment.
What Happens After Diagnosis
Once celiac disease is confirmed, a strict gluten-free diet is the only treatment. Your doctor will likely check your nutritional status, including levels of vitamins A, B12, D, and E, along with iron, hemoglobin, liver enzymes, and bone density. These baseline measurements reveal how much damage the disease has already caused.
Follow-up blood tests track whether your antibody levels are dropping, which signals that your intestine is healing and that your diet is truly gluten-free. If antibodies remain elevated after 12 months on a gluten-free diet, it usually means gluten is still sneaking in somewhere, whether from cross-contamination, mislabeled foods, or hidden sources. Persistent symptoms despite 6 to 12 months of careful gluten avoidance warrant further investigation, potentially including a repeat biopsy to assess whether the intestinal lining has recovered.
Most people see significant symptom improvement within weeks of going gluten-free, though full intestinal healing can take months to years depending on how much damage existed at diagnosis.