Patient education: Celiac disease in adults (Beyond the Basics)

CELIAC DISEASE OVERVIEW — Celiac disease is a condition in which the immune system responds abnormally to a protein called gluten, which then leads to damage to the lining of the small intestine. Gluten is found in wheat, rye, barley, and a multitude of prepared foods. Celiac disease was, in the past, also known as gluten-sensitive enteropathy or celiac sprue.

The small intestine is responsible for absorbing food and nutrients. Thus, damage to the lining of the small intestines can lead to difficulty absorbing important nutrients; this problem is referred to as "malabsorption." Although celiac disease cannot be cured, avoiding gluten usually stops the damage to the intestinal lining and the malabsorption that results. Celiac disease can occur in people of any age, sex, and race.

This article discusses celiac disease in adults. Celiac disease in children is discussed separately. (See "Patient education: Celiac disease in children (Beyond the Basics)".)

CELIAC DISEASE SYMPTOMS — The symptoms of celiac disease vary from one person to another. In its mildest form, there may be no symptoms whatsoever. However, even if you have no symptoms, you may not be absorbing nutrients adequately; this can be detected with blood tests.

Some people with celiac disease have gastrointestinal symptoms, which commonly include:

●Abdominal pain

●Diarrhea

●Bowel movements that are oily and float

●Weight loss

●Feeling bloated, or too full all the time

●Lack of appetite

●Bad gas

Certain other medical conditions are more common in people with celiac disease, including:

●Iron deficiency anemia (low blood count due to lack of iron)

●Osteopenia or osteoporosis (weakening of the bones)

●Diabetes mellitus (type I or so-called juvenile onset diabetes mellitus)

●Thyroid problems (usually hypothyroidism, an underactive thyroid) (see "Patient education: Hypothyroidism (underactive thyroid) (Beyond the Basics)")

●A skin disease called dermatitis herpetiformis (see 'Skin conditions' below)

●Nervous system disorders

●Liver disease

CELIAC DISEASE CAUSES — It is not clear exactly what causes some people to develop celiac disease. Both environmental and genetic factors play a role. Celiac disease occurs widely in Europe, North and South America, Australia, North Africa, the Middle East, and in South Asia. Celiac disease occurs less commonly in people from other parts of Asia or sub-Saharan Africa.

CELIAC DISEASE DIAGNOSIS — Celiac disease can be difficult to diagnose because it can cause so many different symptoms, many of which can also be caused by other conditions. Fortunately, testing is available that can easily distinguish untreated celiac disease from other disorders.

Blood tests — A blood test can determine the blood level of antibodies (specific proteins) that become elevated in people with celiac disease. Over 95 percent of people with untreated celiac disease have elevated antibody levels (called IgA tissue transglutaminase, or IgA tTG), while these levels are rarely elevated in those without celiac disease. Levels of other antibodies (called IgA or IgG deamidated gliadin peptide) are also usually abnormally high in untreated celiac disease.

Before having these tests, it is important to continue eating foods that contain gluten. Avoiding or eliminating gluten could cause the antibody levels to fall to normal, delaying the diagnosis.

Small intestine biopsy — If your blood test is positive, the diagnosis of celiac disease must be confirmed with a biopsy; this involves taking a sample of the intestinal lining and examining it under a microscope. The sample is usually collected during an upper endoscopy, a test that involves swallowing a small flexible instrument with a camera. The camera allows the doctor to examine the upper part of the gastrointestinal system and remove a small piece of the small intestine. The biopsy is not painful. (See "Patient education: Upper endoscopy (Beyond the Basics)".)

Normally, the lining of the small intestine has small finger-like structures that can be seen under a microscope, called "villi." Villi allow the small intestine to absorb nutrients from food. When a person with celiac disease ingests gluten, the villi become flattened, and the body cannot properly absorb nutrients. Once the person removes gluten from their diet, the villi can resume a normal growth pattern. More than 70 percent of people with celiac disease begin to feel better within two weeks after stopping gluten.

"Potential" celiac disease — People with a positive blood test but a normal small intestine biopsy are considered to have potential celiac disease. People with potential celiac disease are not usually advised to eat a gluten-free diet. However, ongoing monitoring (with blood tests) is recommended, and a repeat biopsy may be needed if you develop symptoms. Biopsies should be taken from several areas in the intestine.

"Silent" celiac disease — If you have a positive blood test for celiac disease and an abnormal small intestine biopsy, but you have no other symptoms or signs of celiac disease, you are said to have "silent" celiac disease. It is not clear if adults with silent celiac disease should eat a gluten-free diet, as there is not sufficient evidence that this is beneficial. Blood tests for malabsorption are recommended, and a gluten-free diet may be needed if you have evidence of malabsorption. A temporary trial of the gluten-free diet for several months may be worthwhile to determine whether subtle, unrecognized celiac symptoms (eg, low energy or mild intestinal symptoms) improve.

Testing for malabsorption — You should be tested for nutritional deficiencies if your blood test or biopsy indicates celiac disease. Common tests include measurement of iron, folic acid, or vitamin B12, and vitamin D. You may have other tests if you have signs of mineral or fat-soluble vitamin deficiency, such as changes in taste or smell, poor appetite, changes in your nails, hair, or skin, or diarrhea.

Other tests — Other standard tests include a CBC (complete blood count) and thyroid levels. Once your celiac antibody levels return to normal, you should have a repeat test once per year. (See 'Blood tests' above.)

Many clinicians recommend a test for bone loss 12 months after beginning a gluten-free diet. One method involves using a bone density (DEXA) scan to measure your bone density. The test is not painful and is similar to having an x-ray. If you have significant bone loss, you may need calcium and vitamin D supplements, an exercise program, and possibly a medicine to stop bone loss and encourage new bone growth. (See "Patient education: Bone density testing (Beyond the Basics)".)

CELIAC DISEASE COMPLICATIONS

Nonresponsive celiac disease — At least 10 percent of people with celiac disease experience ongoing symptoms despite adhering to a gluten-free diet. There are many causes, including other food intolerances such as fructose (or other fermentable carbohydrates) malabsorption, food allergies, bacterial overgrowth in the small intestine or conditions such as microscopic colitis, irritable bowel syndrome, pancreatic exocrine insufficiency, or refractory celiac disease. However, the most common cause is ongoing, often inadvertent, gluten ingestion. Thus, an essential first step in evaluating nonresponsive celiac disease is consultation with an experienced celiac dietitian.

Refractory celiac disease — A small percentage of people develop intestinal symptoms that do not improve despite use of a strict gluten-free diet. In other cases, intestinal symptoms initially improve with dietary changes but then return.

People who have these problems may have refractory celiac disease. The cause of this problem is not known. Treatment involves medications that suppress the immune system's abnormal response (eg, steroids). Treatment is important because people with untreated celiac disease can develop anemia, bone loss, and other consequences of malabsorption.

Ulcerative jejunitis — People with refractory celiac disease who do not improve with steroids (glucocorticoids) may have a condition known as ulcerative jejunitis. This rare condition causes the small intestine to develop multiple ulcers that do not heal; other symptoms may include a lack of appetite, weight loss, abdominal pain, diarrhea, and fever. This condition can be difficult to treat. Treatment may require surgery to remove the ulcerated area.

Lymphoma — Cancer of the intestinal lymph system (lymphoma) is a rare complication of celiac disease. Avoiding gluten can usually prevent this complication.

Skin conditions — Celiac disease is associated with a number of skin disorders, of which dermatitis herpetiformis is the most common. Dermatitis herpetiformis is characterized by intensely itchy, raised, fluid-filled areas on the skin, usually located on the elbows, knees, buttocks, lower back, face, neck, trunk, and occasionally within the mouth.

The most bothersome symptoms are itching and burning. This feeling is quickly relieved when the blister ruptures. Scratching causes the area to rupture, dry up, and leave an area of darkened skin and scarring. The condition will improve after eliminating gluten from the diet, although it may take several weeks to see significant improvement. In the meantime, an oral medication called dapsone may be recommended. Dapsone relieves the itching but does not heal the lining of the small intestine; thus, the gluten-free diet is the most effective therapy for people with dermatitis herpetiformis.

CELIAC DISEASE TREATMENT

Gluten-free diet — The cornerstone of treatment for celiac disease is complete elimination of gluten from the diet for life. Gluten is the group of proteins found in wheat, rye, and barley that are toxic to those with celiac disease. Gluten is not only contained in these most commonly consumed grains in the Western world, but is also hidden as an ingredient in a large number of prepared foods as well as medications and supplements.

Maintaining a gluten-free diet can be a challenging task that may require major lifestyle adjustments. Strict gluten avoidance is recommended since even small amounts can aggravate the disease. (See "Management of celiac disease in adults".)

Get help from a dietitian — An experienced celiac dietitian can help you to learn how to eat a gluten-free diet, what foods to avoid, and what foods to add for a nutritionally balanced diet. Your dietitian can tailor your gluten-free diet to your own food preferences, culture, lifestyle, calorie needs, and other medical conditions. They can also recommend gluten-free vitamins/minerals and other supplements, as needed.

Your celiac dietitian can also educate you on grocery shopping, reading labels, food preparation, dining out, and lifestyle resources. Avoiding cross contact (when gluten-free foods come in contact with gluten-containing ingredients or foods) is also very important. Your dietitian can teach you common sources of cross contact in the kitchen, such as crumbs on the counter or sharing butter, jelly, or other condiments with those who eat gluten. Excellent resources are also available from celiac medical centers, organizations, and support groups. (See 'Where to get more information' below.)

Fortunately, life on a gluten-free diet becomes increasingly easier each year due to the rising popularity of gluten-free foods among those with celiac disease, non-celiac gluten sensitivity, and wheat allergies. Excellent gluten-free substitute foods are widely available in supermarkets, health food stores, and online.

General tips

●Avoid foods containing wheat, rye, barley, malt, brewer's yeast, oats (unless uncontaminated, labeled gluten-free oats), and yeast extract and autolyzed yeast extract (unless the source is identified as gluten-free). "Malt" means "barley malt," and should be avoided, unless another grain source is named, such as "corn malt."

●According to US Food and Drug Administration (FDA) regulations issued in 2013, foods with "gluten-free" labeling must contain less than 20 parts per million (ppm) of gluten; this is considered a safe limit for people with celiac disease. The following table has a list of prepared foods that contain or may contain gluten (table 1).

●Naturally gluten-free foods include rice, wild rice, corn, potato, and other grains and foods listed in the table (table 2). However, these foods may be contaminated with wheat, barley, or rye. Choose labeled gluten-free versions of these products. Exceptions are fresh corn, fresh potatoes, plain rice and plain wild rice. These foods may not be labeled gluten-free but are still considered safe to eat. Unless they are labeled gluten-free, dried beans, lentils, and other legumes, such as chickpeas, are allowed by law to contain a certain percentage of foreign grain, including wheat, barley, and/or rye. Whether they are labeled gluten-free or not, sort through them carefully and rinse carefully under running water. Choose labeled gluten-free nuts and seeds when possible, particularly seasoned or dry roasted.

●Typically, people who have just been diagnosed depend on low-fiber and low-nutrient grains and starches like rice, corn, and potatoes because they are familiar with them. Some foods that contain these products are fortified with extra nutrients, but most companies do not fortify their products. In addition, a low fiber diet can lead to constipation. Adding some of the whole gluten-free grains and pseudo-grains (any non-grasses that are used in much the same way as cereal grains), such as quinoa, amaranth, teff, buckwheat, sorghum, and millet, can help improve bowel movements and also increase your nutrients. Make sure they are labeled gluten-free. Be sure to also include plenty of fruits, vegetables, nuts and seeds, legumes and beans (navy, pinto, black, cannellini, etc) in your diet. Add high-fiber foods slowly to give your stomach and intestines time to adjust. When eating a diet rich in fiber, it is important to drink water throughout the day to prevent constipation.

●There is some concern over the potential for increased arsenic and other heavy metal exposure in people with celiac disease. Arsenic can be found in rice, and both children and adults with celiac disease consume a high intake of rice and rice-based products. We need more research to understand whether this exposure may present a long-term health risk to those with celiac disease. In the meantime, it is another reason to rely less on rice and more on other labeled gluten-free grains. When you prepare rice, rinse it before cooking. Cook it in six times more water than rice (as when you cook pasta), and drain the excess water after the rice has finished cooking to remove about 50 percent of the arsenic [1].  

●If a food is regulated by the FDA and is not labeled gluten-free (such as prepared foods and condiments), read the ingredients list and "contains" statement carefully. The word "wheat" will be included if the product is FDA regulated and contains wheat protein. If you do not see any of the following words on the label of an FDA-regulated food (wheat, rye, barley, malt, brewer's yeast, oats, yeast extract, and autolyzed yeast extract) then the product is unlikely to include any gluten-containing ingredients. However, the Food Allergen Consumer Protection Act pertains to ingredients only. It does not cover wheat protein that may be in a product unintentionally due to cross-contact.

●Unlike the FDA, there is no official standard for gluten-free labeling of United States Department of Agriculture (USDA) products. However, if an USDA regulated product has a gluten-free label, it should meet the same standard as FDA products. See USDA labeling information in the resources listed below.

●Distilled alcoholic beverages and vinegars, as well as wine, are gluten-free unless gluten-containing flavorings are added after production. However, malt beverages, including beer, are not considered gluten-free. There are specially produced beers that do not use malted barley that are labeled gluten-free and can be consumed on a gluten-free diet. Avoid beer that is labeled as gluten-removed or gluten-reduced. Please note that malt vinegar is not gluten-free.

●You may not tolerate lactose initially while your intestines are healing. If you tolerated lactose before your diagnosis, you may be able to tolerate it again after the intestine heals. In the meantime, choose lactose-reduced or lactose-free products if your symptoms are worsened by dairy products. Choose labeled gluten-free, dairy-free alternatives, such as rice, pea, soy, or nut (almond, hazelnut) beverages that are enriched with calcium and vitamin D. Keep in mind that gluten-free rice and nut milks have minimal protein per serving compared with cow's or soy milk. Gluten-free lactase enzyme supplements are also available, which may help you to tolerate foods that contain lactose.

●Discuss your need for labeled gluten-free calcium and vitamin D supplements with your health care provider or dietitian.

●A small percentage of people with celiac disease cannot tolerate gluten-free oats for several reasons. Pure oats are naturally gluten free, but most are grown in or near barley, rye, and wheat. They can also be processed on the same equipment which contaminates them and makes them unsafe for someone with celiac disease to eat. At this time, there are two methods to produce gluten-free oats. Manufacturers of "purity protocol" oats follow several steps to avoid cross contact, such as separate equipment and facilities that do not share or process gluten-containing grains. Other companies use mechanical and optical sorting methods to "clean" oats. Their special equipment sorts oats from gluten-containing grains based on the differences in size, shape, and other factors. Regardless of the type of gluten-free oats, proper, rigorous testing by the company is the most important step to exclude cross-contact with gluten.

All oats consumed, at the very least, must be labeled gluten-free or certified gluten-free. If you choose to eat gluten-free oats, first talk to your doctor who can check your tTG-IgA level and monitor any symptoms. Limit your intake of gluten-free oats to no more than 50 grams (approximately 1/2 cup dry rolled oats or 1/4 cup dry steel-cut oats) per day. If tolerated, you may be able to discuss eating more than 1/2 cup per day under the supervision of your doctor. People with severe or hard to manage disease should avoid even gluten-free oats.

Is strict gluten avoidance really necessary? — People who have been diagnosed with celiac disease but have no symptoms often find it difficult to follow a strict gluten-free diet. Indeed, some health care providers have questioned the need for a gluten-free diet in this group. However, certain factors support a gluten-free diet, even in those without symptoms:

●Strictly following a gluten-free diet sometimes helps you to feel more energetic and have an improved sense of health and wellbeing.

●Some people with celiac disease have vitamin or nutrient deficiencies that do not cause them to feel ill, such as anemia due to iron deficiency or bone loss due to vitamin D deficiency. However, these deficiencies can cause problems over the long term.

●Untreated celiac disease can increase the risk of developing certain types of gastrointestinal cancer. This risk can be reduced by eating a gluten-free diet.

Ongoing monitoring — Once a person has been on a gluten-free diet for at least four to six weeks, blood tests can be used to confirm that antibody levels are declining (see 'Blood tests' above). The health care provider will also monitor the person for any new or worsening symptoms.

IMPLICATIONS FOR THE FAMILY — Eliminating gluten requires a major lifestyle change for you as well as your family. However, with time and practice, it will be easier to know which foods, medications, supplements, and oral care products contain gluten and what alternatives are available. Although eating out can be challenging at first, restaurants have become increasingly interested in serving people with celiac disease by offering a gluten-free menu or ingredient substitutions.

Families also need to be aware of their increased risk of celiac disease, as there is a genetic component. If you have been diagnosed with celiac disease, your first-degree relatives (parents, siblings, children) should consider being tested as well, especially if anyone has signs or symptoms of the condition. Testing is typically done with a blood antibody test, as described above. (See 'Blood tests' above.)

WHERE TO GET MORE INFORMATION — Your health care provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for health care professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Celiac disease (The Basics)
Patient education: Microscopic colitis (The Basics)
Patient education: Gluten-free diet (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Celiac disease in children (Beyond the Basics)
Patient education: Hypothyroidism (underactive thyroid) (Beyond the Basics)
Patient education: Upper endoscopy (Beyond the Basics)
Patient education: Bone density testing (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Diagnosis of celiac disease in adults
Management of celiac disease in adults
Epidemiology, pathogenesis, and clinical manifestations of celiac disease in adults

Resources — The following resources also provide reliable information and/or support for people living with celiac disease or non-celiac gluten sensitivity.

●Academy of Nutrition and Dietetics (formerly American Dietetic Association)

(www.eatright.org)

●Beyond Celiac

(www.beyondceliac.org)

●Celiac Disease Foundation

(www.celiac.org)

●Gluten Intolerance Group of North America

https://gluten.org/

●National Celiac Association

(www.nationalceliac.org)

●National Institute of Diabetes and Digestive and Kidney Diseases

(www.niddk.nih.gov)

●National Library of Medicine

(www.nlm.nih.gov/medlineplus/celiacdisease.html)

●Society for the Study of Celiac Disease

(www.theceliacsociety.org)

●FDA and USDA Labeling

•https://www.fda.gov/Food/GuidanceRegulation/GuidanceDocumentsRegulatoryInformation/Allergens/ucm362880.htm

•https://www.glutenfreewatchdog.org/news/usda-regulated-foods-and-gluten-free-labeling/

•https://www.glutenfreewatchdog.org/news/words-to-look-for-in-usda-regulated-foods-not-labeled-gluten-free/

●Thompson T. Academy of Nutrition and Dietetics Pocket Guide to Gluten-Free Strategies for Clients with Multiple Diet Restrictions, 2^nd edition. Academy of Nutrition and Dietetics. Chicago 2016.

●Celiac List-serv

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