What symptoms should make you suspect celiac disease
Celiac disease shows up differently in different people, and some people have no obvious symptoms at all. The most common signs are digestive: chronic diarrhea or constipation, bloating, gas, and stomach pain that comes and goes. Many people describe it as feeling constantly uncomfortable after eating, or having a swollen belly that doesn't match how much they ate.
Beyond the gut, celiac disease can cause fatigue that doesn't improve with rest, joint or bone pain, headaches, or a skin rash called dermatitis herpetiformis—small blistering bumps usually on the elbows, knees, or buttocks. Some people lose weight without trying, or fail to gain weight normally if they're children. Others experience anemia (low iron), which shows up as shortness of breath or persistent tiredness.
The catch is that these symptoms overlap with dozens of other conditions. Bloating could be irritable bowel syndrome, lactose intolerance, or just eating too fast. Fatigue could be depression, thyroid disease, or sleep apnea. You cannot diagnose celiac disease from symptoms alone—you need blood tests and, usually, a biopsy.
Key Takeaways
- Celiac disease causes digestive symptoms in some people and no obvious symptoms in others, so you cannot rule it out based on how you feel.
- A blood test for tissue transglutaminase (tTG) antibodies is the first step, and you must be eating gluten regularly when you get tested or the result will be falsely negative.
- If your blood test is positive, your doctor will usually order an upper endoscopy with a biopsy to confirm the diagnosis.
- Celiac disease runs in families, so if a close relative has it, you have a higher chance of having it too even if you feel fine.
- You should not start a gluten-free diet before testing, because it will make the blood test and biopsy unreliable.
The blood test that detects celiac disease
The standard first test is a blood test for tissue transglutaminase (tTG) antibodies, usually written as tTG-IgA. Your immune system makes these antibodies when you eat gluten if you have celiac disease. The test is inexpensive and widely available through any primary care doctor or gastroenterologist.
The critical thing: you must be eating gluten regularly when you have the test drawn. If you have already stopped eating gluten, the antibodies will disappear and the test will come back negative even if you have celiac disease. You need to eat bread, pasta, cereals, or other gluten-containing foods for at least a few weeks before the test—ideally longer. If you have already gone gluten-free, you would need to reintroduce gluten for several weeks before testing, which is uncomfortable but necessary for an accurate result.
Some people also have low total IgA levels, which can make the tTG-IgA test unreliable. If that is the case, your doctor may order a different antibody test called deamidated gliadin peptide (DGP) instead. Ask your doctor which test they are ordering and why.
What happens if the blood test is positive
A positive tTG antibody test is strong evidence of celiac disease, but it is not the final diagnosis. Your doctor will usually refer you to a gastroenterologist for an upper endoscopy with a biopsy. This is a procedure where a thin tube with a camera is passed down your throat into your small intestine, and tiny tissue samples are taken and examined under a microscope.
In celiac disease, the lining of the small intestine becomes flattened and damaged. The biopsy shows this damage, which confirms the diagnosis. The procedure takes 15 to 30 minutes and is usually done under light sedation. You will need someone to drive you home afterward because of the sedation.
Like the blood test, the biopsy is only reliable if you are still eating gluten. If you have already started a gluten-free diet, the intestinal lining will begin to heal and the biopsy may look normal even though you have celiac disease. You need to stay on a regular diet until after the biopsy is done.
When you should get tested even without symptoms
Celiac disease runs in families. If a parent, sibling, or child has celiac disease, you have roughly a 1 in 10 chance of having it too, even if you feel completely fine. Many people with celiac disease have no digestive symptoms at all—they only discover it because a relative was diagnosed and they got tested.
Your doctor may also recommend testing if you have certain other conditions that are more common in people with celiac disease, such as type 1 diabetes, osteoporosis, or thyroid disease. Some people are diagnosed with celiac disease only after years of being treated for anemia or fatigue that turned out to be caused by undiagnosed celiac disease.
If celiac disease runs in your family or you have one of these related conditions, talk to your doctor about whether testing makes sense for you. There is no harm in testing if you have no symptoms, and finding out early means you can start a gluten-free diet before complications develop.
Why you should not go gluten-free before testing
It is tempting to try a gluten-free diet on your own if you suspect celiac disease, especially if you feel better without gluten. But doing this before you have been tested will make diagnosis much harder or impossible. Both the blood test and the biopsy depend on your immune system actively reacting to gluten, which only happens if you are eating it.
If you start a gluten-free diet and then get tested, a negative result does not mean you don't have celiac disease—it means the test cannot tell. You would then have to go back on gluten for weeks to retest, which is unpleasant and defeats the purpose of going gluten-free in the first place. Get tested first, get a diagnosis, and then start the diet with confidence that you know what you are treating.
What to expect at your doctor's appointment
When you see your doctor about possible celiac disease, bring a list of your symptoms and when they started, any family history of celiac disease or related conditions, and any other health problems you have. Your doctor will ask about your digestive symptoms, weight changes, fatigue, and whether anyone in your family has celiac disease.
Be honest about your diet. If you have already cut out gluten or are thinking about it, tell your doctor before they order the blood test. They may want you to eat gluten for a period of time before testing, or they may order a different test. If you have already been gluten-free for weeks or months, your doctor needs to know that too, because it affects how to interpret the results.
Your doctor will order the tTG antibody blood test. If it is positive, they will refer you to a gastroenterologist for the endoscopy and biopsy. If it is negative but your symptoms are still suggestive of celiac disease, your doctor may order additional tests or refer you to a specialist anyway.
Other conditions that look like celiac disease
Not everyone with digestive symptoms has celiac disease. Non-celiac gluten sensitivity is a real condition where people feel better on a gluten-free diet but do not have celiac disease or wheat allergy—their blood tests and biopsies are normal. There is no test for non-celiac gluten sensitivity; it is diagnosed by ruling out celiac disease and wheat allergy first, then seeing if symptoms improve on a gluten-free diet.
Wheat allergy is different from celiac disease. It causes an allergic reaction (itching, swelling, hives, or anaphylaxis) usually within minutes to hours of eating wheat. It is diagnosed with a skin prick test or blood test for wheat-specific IgE antibodies, not the celiac disease tests. People with wheat allergy can usually eat other grains like barley and rye.
Irritable bowel syndrome, lactose intolerance, and inflammatory bowel disease (Crohn's disease or ulcerative colitis) all cause similar symptoms. Your doctor will help sort out which condition you have based on your symptoms, test results, and sometimes additional testing.
Frequently Asked Questions
Can I have celiac disease if I feel fine?
Yes. Many people with celiac disease have no digestive symptoms at all. They may have anemia, fatigue, bone pain, or no symptoms whatsoever. If celiac disease runs in your family, you should consider testing even if you feel well.
What if my blood test is negative but I still think I have celiac disease?
A negative test is reliable only if you were eating gluten regularly when the test was done. If you had already cut out gluten, the test cannot tell you anything. Talk to your doctor about whether you should reintroduce gluten and retest, or whether another condition might explain your symptoms.
How long does it take to get a diagnosis?
The blood test results usually come back within a week or two. If it is positive, getting an appointment with a gastroenterologist for the biopsy can take anywhere from a few weeks to a few months depending on how busy the clinic is. The biopsy results typically come back within a week.
Do I need the biopsy if my blood test is positive?
Most doctors recommend it because the biopsy confirms the diagnosis and shows how much damage the intestine has. In rare cases, a very high antibody level plus strong symptoms may be enough, but your doctor will discuss this with you.
What should I eat while waiting for my test?
Eat your normal diet, including gluten-containing foods like bread, pasta, and cereals. Do not change your diet before testing. If you have already been avoiding gluten, tell your doctor before the blood test is drawn.