Celiac disease is a disease of the digestive system in which the inside lining of the small intestine (mucosa) is damaged after eating wheat, rye, oats, or barley, resulting in interference with the absorption of nutrients from food.
Celiac disease occurs when the body reacts abnormally to gluten, a protein found in grains, including wheat, rye, barley, and possibly oats. When someone with celiac disease eats foods containing gluten, that person's immune system causes an inflammatory response in the small intestine, which damages the tissues and results in impaired ability to absorb nutrients from foods (malabsorption). The inflammation and malabsorption create wide-ranging problems in many systems of the body. Since the body's own immune system causes the damage, celiac disease is classified as an autoimmune disorder.
Each person with celiac disease is affected differently. When food containing gluten reaches the small intestine, the immune system begins to attack a substance called gliadin, which is found in the gluten. The resulting inflammation causes damage to the delicate finger-like structures in the intestine, called villi, where food absorption actually takes place. This damage is referred to as villus atrophy. The patient may experience a number of symptoms related to the inflammation and the chemicals it releases, and/or the lack of ability to absorb nutrients from food, which can cause malnutrition.
Celiac disease may be discovered at any age, from infancy through adulthood. The disorder is more commonly found among white Europeans and in people of European descent. It is very unusual to find celiac disease in African or Asian people. The exact incidence of the disease is uncertain. Estimates vary from one in 5,000, to as many as one in every 300 individuals with this background. The prevalence of celiac disease seems to be different from one European country to another and between Europe and the United States. This discrepancy may be due to differences in diet and/or the possibility that the disease goes unrecognized in some areas. One study of random blood samples tested for celiac disease in the United States showed one in 250 testing positive. It is clearly underdiagnosed, probably because the symptoms are attributed to another problem, and physicians and laboratory technicians lack knowledge about celiac disease.
Because celiac disease has a hereditary influence or genetic component, close relatives (especially first-degree relatives, such as children, siblings, and parents) have a higher risk of being affected with the condition. The chance that a first-degree relative of someone with celiac disease has the disease is about 10 percent.
Causes and symptoms
The pattern of inheritance is complicated regarding this disease. The type of inheritance pattern that celiac disease follows is called multifactorial (caused by many factors, both genetic and environmental). Researchers think that several factors must exist in order for the disease to occur. The patient must have a genetic predisposition to develop the disorder. Then something in their environment acts as a stimulus, or trigger, to their immune system, causing the disease to become active for the first time. For conditions with multifactorial inheritance, people without the genetic predisposition are less likely to develop the condition with exposure to the same triggers, or they may require more exposure to the stimulus before developing the disease than someone with a genetic predisposition. Stimuli that may provoke a reaction include surgery, especially gastrointestinal surgery; a change to a low fat diet, which includes an increased number of wheat-based foods; severe emotional stress; or a viral infection. The combination of genetic susceptibility and an outside agent leads to celiac disease.
The most commonly recognized symptoms of celiac disease relate to the improper absorption of food in the gastrointestinal system. Many patients with gastrointestinal symptoms will have diarrhea and fatty, greasy, unusually foul-smelling stools. The patient may complain of excessive gas (flatulence), distended abdomen, weight loss, and generalized weakness. Not all people have digestive system complications; some people only have irritability or depression. Irritability is one of the most common symptoms in children with celiac disease.
Not all individuals with celiac disease exhibit typical symptoms. As more is learned about celiac disease, it has become evident that the disease has many variations that may not produce typical symptoms. Unrecognized and therefore untreated celiac disease may cause or contribute to a variety of other conditions. The decreased ability to digest, absorb, and utilize food properly (malabsorption) may cause anemia (low red blood count from iron deficiency) or easy bruising from a lack of vitamin K. Poor mineral absorption may result in osteoporosis, or brittle bones, which may lead to bone fractures. Vitamin D levels may be insufficient and bring about a softening of bones (osteomalacia), which produces pain and bony deformities, such as flattening or bending. Defects in the tooth enamel, characteristic of celiac disease, may be recognized by dentists. Celiac disease may be discovered during medical tests performed to investigate failure to thrive in infants or lack of proper growth in children and adolescents. People with celiac disease may also experience lactose intolerance because they do not produce enough of the enzyme lactase, which breaks down the sugar in milk into a form the body can absorb. Other symptoms can include muscle cramps, fatigue, delayed growth, tingling or numbness in the legs (from nerve damage), pale sores in the mouth (called aphthus ulcers), tooth discoloration, or missed menstrual periods (due to severe weight loss).
A distinctive, painful skin rash, called dermatitis herpetiformis, may be the first sign of celiac disease in adults but rarely occurs in children with celiac disease.
Many disorders are associated with celiac disease, although the nature of the connection is unclear. One type of epilepsy is linked to celiac disease. Once their celiac disease is successfully treated, a significant number of these patients have fewer or no seizures. Patients with alopecia areata, a condition in which hair loss occurs in sharply defined areas, have been shown to have a higher risk of celiac disease than the general population. There appears to be a higher percentage of celiac disease among people with Down syndrome, but the link between the conditions was unknown as of 2004.
Several conditions attributed to a disorder of the immune system have been associated with celiac disease. People with insulin-dependent diabetes (type I) have a much higher incidence of celiac disease. One source estimates that as many as one in 20 insulin-dependent diabetics may have celiac disease. Patients with other conditions in which celiac disease may be more commonly found include those with juvenile chronic arthritis, some thyroid diseases, and IgA deficiency.
There is an increased risk of intestinal lymphoma, a type of cancer, in individuals with celiac disease. Successful treatment of the celiac disease seems to decrease the chance of developing lymphoma.
When to call the doctor
A doctor should be consulted when a child exhibits symptoms characteristic of this disease.
Because of the variety of ways celiac disease can manifest itself, it is often not discovered promptly. Its symptoms are similar to many other conditions including irritable bowel syndrome, Crohn's disease, ulcerative colitis, diverticulosis, intestinal infections, chronic fatigue syndrome, and depression. The condition may persist without diagnosis for so long that the patient accepts a general feeling of illness as normal. This acceptance leads to further delay in identifying and treating the disorder. It is not unusual for the disease to be identified in the course of medical investigations for seemingly unrelated problems.
If celiac disease is suspected, based on symptoms, physical appearance, or delayed growth, a blood test should be ordered. This test looks for the antibodies to gluten (called antigliadin, anti-endomysium, and antireticulin) that the immune system produces in celiac disease. Antibodies are chemicals produced by the immune system in response to substances such as germs and other potentially harmful substances. Some experts advocate not just evaluating patients with symptoms, but using these blood studies as a screening test for high-risk individuals, such as those with relatives (especially first-degree relatives) known to have the disorder. An abnormal result points toward celiac disease, but further tests are needed to confirm the diagnosis. Because celiac disease affects the ability of the body to absorb nutrients from food, several tests may be ordered to look for nutritional deficiencies. For example, doctors may order a test of iron levels in the blood because low levels of iron (anemia) may accompany celiac disease. Doctors may also order a test for fat in the stool, since celiac disease prevents the body from absorbing fat from food.
If these tests are suspicious for celiac disease, the next step is a biopsy (surgical removal of a tiny piece of tissue) of the small intestine. This is usually done by a gastroenterologist, a physician who specializes in diagnosing and treating bowel disorders. It is generally performed in the office or in a hospital's outpatient department. The patient remains awake but is sedated. A narrow tube, called an endoscope, is passed through the mouth, down through the stomach, and into the small intestine. A small sample of tissue is taken and sent to the laboratory for analysis. If it shows a pattern of tissue damage characteristic of celiac disease, the diagnosis is established.
The only treatment for celiac disease is a gluten-free diet (GFD). This diet is easy for the doctor to prescribe but may be difficult for a child to follow. For most people, adhering to this diet stops symptoms and prevents damage to the intestines. Damaged villi can be functional again in three to six months. This diet must be followed permanently, however. The fact that people had symptoms that were cured by the GFD is further evidence that the diagnosis was correct.
The physician will periodically recheck the level of antibody in the child's blood. After several months, the small intestine is biopsied again. If the diagnosis of celiac disease was correct (and the child followed the rigorous diet), healing of the intestine will be apparent. Most experts agree that it is necessary to follow these steps in order to be sure of an accurate diagnosis. Disorders other than celiac disease can cause a similar type of villus atrophy, especially in children under two years of age, so rechecking the intestine is especially important for very young children. If healing is evident, then gluten is reintroduced to the diet and a third biopsy is performed
A child with undiagnosed celiac disease may become very ill with severe diarrhea and malnutrition. Corticosteroids such as prednisone and intravenous (IV) fluids may be temporarily given while the child begins a GFD. Because celiac disease is diagnosed more quickly than in the past, corticosteroids are seldom required.
Although there is no risk and much potential benefit to the use of GFD for treatment of celiac disease, the widespread use of gluten-containing grains in Western cultures makes adapting to a gluten-free diet challenging. Gluten is present in any product that contains wheat, rye, barley, or oats. It helps make bread rise and gives many foods a smooth, pleasing texture. In addition to the many obvious places gluten can be found in a normal diet, such as breads, cereals, and pasta, there are many hidden sources of gluten. Thickening agents, emulsifiers, fillers, flavor enhancers, and food stabilizers as well as products used in food packaging may contain gluten. Gluten may even be present on surfaces used for food preparation or cooking.
Fresh foods that have not been artificially processed, such as fruits, vegetables, and meats, are permitted as part of a GFD. Gluten-free foods can be found in health food stores and in some supermarkets. Mail-order food companies often have a selection of gluten-free products. Help in dietary planning is available from dieticians (healthcare professionals specializing in food and nutrition) or from support groups for individuals with celiac disease. There are many cookbooks on the market specifically for those on a GFD.
Treating celiac disease with a strict GFD is almost always completely effective. Gastrointestinal complaints and other symptoms are alleviated. Secondary complications, such as anemia and osteoporosis, resolve in almost all patients. People who have experienced lactose intolerance related to their celiac disease usually see those symptoms subside as well.
Once the diet has been followed for several years, individuals with celiac disease have similar mortality rates as the general population. However, about 10 percent of people with celiac disease develop a cancer involving the gastrointestinal tract (both carcinoma and lymphoma).
A few patients develop a refractory type of celiac disease, in which the GFD no longer seems effective. Once the diet has been thoroughly assessed to ensure no hidden sources of gluten are causing the problem, medications may be prescribed. Steroids or immunosuppressant drugs are often used to try to control the disease. It is unclear whether these efforts meet with much success.
Experts emphasize the need for lifelong adherence to the GFD to avoid the long-term complications of this disorder. They point out that although the disease may have symptom-free periods if the diet is not followed, silent damage continues to occur. Celiac disease cannot be outgrown or cured, according to medical authorities.
There is no way to prevent celiac disease. However, the key to decreasing its impact on overall health is early diagnosis and strict adherence to the prescribed GFD.
For parents used to preparing gluten-containing meals, searching for and cooking with gluten-free products may be difficult at first. Changing cooking habits will be easier if initially gluten-free recipes and food products are used. When they use any commercial food products, they must read carefully the list of ingredients. Although ingredients are listed in order of decreasing content, any product containing the smallest of amount of gluten must be avoided. Many food manufacturers are willing to provide additional information about their products. Most food labels contain addresses of the manufacturers and many include a toll-free telephone number. Some restaurants have ingredient lists for their products posted in the restaurant or available on request.
When a child with celiac disease eats at a friend's house, the friend's parent should be aware of the child's dietary limitations. The child may have to take lunch from home to eat at school, unless the school has a dietician who can ensure that gluten-free food is provided for the child.
Family support is important in ensuring acceptance of the diet. The child must not be made to feel that he/she is abnormal and a nuisance to the family. After the GFD is begun, the benefits to the child with celiac disease will initially be obvious and enthusiastically accepted. However, as the child gets older, the period of ill health may be forgotten, and the child may be reject the diet, especially during adolescence, when there is a desire for conformity. Unfortunately, in older children, the symptoms may not reappear immediately although intestinal damage is occurring. The child may interpret the delay
Antibody—A special protein made by the body's immune system as a defense against foreign material (bacteria, viruses, etc.) that enters the body. It is uniquely designed to attack and neutralize the specific antigen that triggered the immune response.
Antigen—A substance (usually a protein) identified as foreign by the body's immune system, triggering the release of antibodies as part of the body's immune response.
Gluten—A protein found in wheat, rye, barley, and oats.
Immune system—The system of specialized organs, lymph nodes, and blood cells throughout the body that work together to defend the body against foreign invaders (bacteria, viruses, fungi, etc.).
Villi—Tiny, finger-like projections that enable the small intestine to absorb nutrients from food.
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Judith Sims, MS Amy Vance, MS, CGC