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What Is Celiac Disease?

Celiac disease (CD), also sometimes called gluten intolerance or non-tropical sprue is a condition in which a person’s intestines cannot digest part of the protein in wheat, as well as similar proteins in other grains including barley and rye. This causes a number of symptoms in "classic" cases of celiac disease. Symptoms include abdominal pain, cramps, bloating, and diarrhea.

Instead of wheat being taken in as nutrition, gluten in wheat actually damages the intestinal lining of a person with celiac disease. This means that the small intestines lose some of their ability to absorb food. This is particularly dangerous for young children, who may lose weight instead of growing and gaining weight. Very young children may have what is called "failure to thrive" because they are not getting enough calories to develop normally.

There are a variety of problems related to the fact that vitamins are also not absorbed, causing everything from iron-deficiency anemia to brittle bones (osteoporosis) from a lack of calcium.

It was previously believed that this disease usually appeared in childhood, and the affected children were very ill. This is called "classic celiac disease" and does occur. However, it is now known that there can be "atypical" or even "silent" cases of CD. Adults may not have cramps and diarrhea, or significant weight loss. Their celiac disease may come to light because of the secondary problems described above, like anemia or osteoporosis. CD causes many other symptoms, from sores in the mouth and epilepsy to infertility. One type of celiac disease is seen on the skin, and is called dermatitis herpetiformis.

In the United States, as well as most of Europe, the percentage of people with celiac disease is about 1%. Research is showing that there may be rates that high in other geographical areas as well.

Celiac disease can be inherited, but the genetics are not straightforward. Children who have a parent with celiac disease have about a 10% chance of having CD. There are specific genes necessary for the development of celiac disease called HLA types, and the ones related to CD are HLA-DQ2 and HLA-DQ8. Not everyone with these genes has CD.

There are other risk factors for celiac disease, such as autoimmune disorders including rheumatoid arthritis, type 1 diabetes, psoriasis and certain kinds of thyroid problems.

How is celiac disease diagnosed?

It is not always easy for doctors to realize someone has celiac disease. This disease used to be considered extremely rare. There is increasing awareness in the medical community of the fact that many people with celiac disease have not been diagnosed. They may have been misdiagnosed and told they had irritable bowel disease or some other reason for abdominal symptoms. Or they may have no abdominal symptoms at all but one of the associated problems such as osteoporosis at an early age. Doctors are much more likely to look for celiac disease in any child or adult with abdominal symptoms, as well as those with diseases related to vitamin deficiency.

A doctor must have number of tests performed to diagnose CD.

There are blood tests that are very good at screening for celiac disease. Blood tests have improved over time, with the more accurate tests being used now instead of the older tests. Most doctors will order antibodies to tissue transglutaminase (TTG), anti-endomysial antibodies (EMA), and/or antibodies to deamidated gliadin peptides (DGP-AGA). There are different kinds of antibodies, so that doctors may also order both IgA and IgG antibodies or may measure a person’s total IgA to see if they can make the antibodies the tests look for.

Other blood tests can be done to look for secondary problems, for example, vitamin levels to look for deficiencies leading to anemia.

If some or all of the antibody tests are positive, especially in a person with symptoms of celiac disease or other disorders known to be related to celiac disease, the diagnosis must be confirmed by a biopsy of the part of the small bowel called the duodenum. This is done via a procedure called endoscopy, in which a tube goes down the esophagus through the stomach and into the small intestine. The doctor doing the procedure can see what the lining of the intestine looks like, and take samples (four to six) for biopsy.

The appearance of the lining under a microscope showing what is called "villous atrophy" is the "gold standard test" to determine if someone has celiac disease. Villous atrophy demonstrates that the intestinal lining has been seriously damaged. This test needs to be done essentially 100% of the time to be sure of the diagnosis. However, a person must be eating a normal diet containing gluten for the biopsy to show the results. Most people with CD on a gluten-free diet will eventually have normal biopsies.

How is celiac disease treated?

The only treatment for celiac disease is a completely gluten-free diet. Although there are medications under research, there is nothing close to being ready to treat people. The only way to allow the intestines to heal and work normally is to stay on an absolutely gluten-free diet.

Once diagnosed, a person with celiac disease must go on the diet for life. There are many resources available to people with CD now to help them with this challenge, from organizations with online presences, to gluten-free products available in many stores as well as online. There are gluten-free cookbooks and gluten-free restaurants.

Media attention has also been given to celebrities with children who have celiac disease or who have CD themselves. They also promote a gluten-free diet as a healthy diet and as a treatment for other problems not proven to be related to CD or really treatable with a gluten-free diet, like autism or behavioral problems in children.

The attention by celebrities has been a boon for people with CD who usually had few choices when looking for good tasting, gluten-free food. There are now thousands and thousands of gluten-free products in stores and restaurants.

However, if you do not have celiac disease or a definite allergy to wheat (a separate problem), a gluten-free diet is not healthier than a well-balanced regular diet. It is more difficult to follow, may not taste as good, and costs more money. No one will really stick to the diet unless they have a very good reason.

What happens after starting the gluten-free diet?

If a person with CD is on a gluten-free diet, feels well and any other problems are corrected, it is not considered essential to redo the biopsy to confirm improvement as was done in the past. Eventually the blood tests will become normal.

If antibodies do not decrease or symptoms continue, there may be a need for another biopsy.

There is a small subgroup of patients with celiac disease who do not improve, even on a completely gluten-free diet, and they need further evaluation. However, the most common cause of continued symptoms or abnormal tests is that the diet is not completely gluten free, either accidentally or because someone has had the occasional lapse and eaten food with gluten.

Anyone who has celiac disease, or thinks they might have celiac disease, needs to be under the care of a physician. Most doctors can order the appropriate laboratory tests. The biopsy, however, must be done by a specialist in the gastrointestinal tract, called a gastroenterologist. This is also the type of doctor that should be following a patient with celiac disease, especially if symptoms are not improving. Other doctors may need to be consulted if someone with celiac disease has other autoimmune disorders.

If you think you might have celiac disease because of your symptoms, family history, or other medical problems, you should bring this to the attention of your doctor.

References

Hoffenberg, E. Celiac Disease. In: Bishop W.P., ed. Pediatric Practice Gastroenterology. New York, NY.: McGraw-Hill Professional; 2010: 285-278.

Lionetti E., Catassi C. New Clues in Celiac Disease Epidemiology, Pathogenesis, Clinical Manifestations, and Treatment. International Reviews of Immunology 2011; 30: 219–231.

Schuppan D., Junker Y., Barisani D. Celiac Disease: From Pathogenesis to Novel Therapies. Gastroenterology 2009;137:1912–1933.

Volta U., Villanacci V. Celiac disease: diagnostic criteria in progress. Cellular & Molecular Immunology 2011; 8: 96–102.





Anna Kaplan MD

Dr. Anna Kaplan graduated with a BA in English literature from Pomona College in 1975. She received her MD from U.S.C. School of Medicine in 1979. A three-year residency (training period) in family practice followed, and she was certified by the American Board of Family Physicians in 1982. She recertified, a normal procedure, in 1988 and 1995. She retired from active practice after 15 years, but keeps up with medicine via continuing medical education.

Dr. Kaplan has written in the medical field for both consumers as well as professionals. She has also authored hundreds of articles on other subjects.


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