Celiac.com 03/21/2007 - Celiac disease is an inherited autoimmune disorder marked by an inflammatory condition in the small intestine that triggers when genetically susceptible individuals consume wheat. Symptoms of celiac most commonly begin around age two, after wheat has been introduced into the diet, or in the third and fourth decades of adult life.
In genetically susceptible people, the ingestion of wheat gluten protein triggers an inflammatory reaction in the small bowel that causes a collapse of the villi, the small finger-like projections responsible for nutrient absorption. This greatly reduces the amount of surface area available for nutrient, fluid and electrolyte absorption. The extent of this intestinal damage generally correlates to the severity of the symptoms.
Celiac disease can also occur in asymptomatic individuals who have associated conditions. Recent studies show the prevalence of celiac in children under 15 years in the general population to be 3 to 13 per 1,000 children, or approximately 1:300 to 1:80 children. A figure of 1 in 133 people is commonly used as an average for rates of celiac disease in the general population.
Celiac Disease Diagnosis
Celiac disease can be challenging to diagnose, because its symptoms are often similar to those of other diseases. Celiac disease is easily taken for other diseases such as Crohns disease, chronic fatigue syndrome, diverticulitis, various intestinal infections, irritable bowel syndrome, iron-deficiency anemia caused by menstrual blood loss. Thus, celiac disease is often misdiagnosed, and greatly under-diagnosed.
Celiac practice guidelines call for routine screening of anyone with a family history of celiac disease or of disorders such as thyroid disease, anemia of unknown cause, type 1 diabetes or other immune disorders or Downs syndrome. Otherwise, patients are generally screened case by case according to individual symptoms.
Considerations for Celiac Disease
As a general practice, celiac disease should be considered in the earliest stages of differential diagnosis of children with persistent diarrhea, especially with failure to thrive. Celiac disease should also be considered in the differential diagnosis of children with persistent GI symptoms, including recurrent abdominal pain, constipation and vomiting, and any other GI issues commonly associated with celiac disease.
Testing is recommended for children with celiac-associated non-gastrointestinal symptoms, such as delayed puberty, dental enamel hypoplasia of permanent teeth, dermatitis herpetiformis, iron-deficient anemia resistant to oral iron, osteoporosis, and short stature. Testing is also recommended for asymptomatic children whose relatives have celiac, and those who have celiac-associated conditions, such as autoimmune thyroiditis, Down syndrome, selective IgA deficiency, Turner syndrome, type 1 diabetes mellitus, or Williams syndrome.
Celiac practice guidelines call for testing asymptomatic children who belong to at-risk groups at around 3 years of age, as long as they have eaten gluten regularly for at least 1 year before testing.
First-degree relatives of individuals with celiac disease may or may not manifest symptoms of the disease.
Predisposition to gluten sensitivity has been mapped to the major histocompatibility (MHC) D region on chromosome 6. The most important HLA haplotype is DQw2, which is often in linkage with DR3. Other important HLA haplotypes identified are DR7 and DPB 1, 3, 4.1 and 4.2.
The sites on these MHC class 2 expressed proteins responsible for interacting with gliadin and host T cell receptors thereby sensitizing the intestine to gluten have not been identified.
Therefore, guidelines call for regular testing of asymptomatic individuals with negative serological tests, and who belong to at-risk groups. Treatment guidelines do not presently call for routinely testing autistic children for celiac disease, as there is no evidence that celiac is more in autistic children than in the general population.
Celiac Disease Testing
There is currently no test for diagnosing celiac disease with 100% certainty. For most people, the disappearance of symptoms, and/or the appearance of a "normal" biopsy following the adoption of a gluten-free diet provide the strongest evidence for celiac disease or gluten intolerance.
A blood test, such as anti-tissue transglutaminase and anti-endomysial antibodies, can detect abnormally levels of antibodies, and is often used in the initial detection of celiac in people who are most likely to have the disease, and for those who may need further testing.
Based on the current evidence and practical considerations, including accuracy, reliability, and cost, measurement of IgA antibody to human recombinant tissue transglutaminase (TTG) is recommended for initial testing for celiac disease. Although as accurate as TTG, measurement of IgA antibody to endomysium (EMA) is observer dependent and therefore more subject to interpretation error and added cost. Because of the inferior accuracy of the antigliadin antibody tests (AGA), the use of AGA IgA and AGA IgG tests alone is no longer recommended for detecting celiac disease.
Several serological markers are useful in diagnosing celiac disease. The first of these is IgG class antigliadin antibody (AGA). This antibody is sensitive to gluten, but it is also found in other diseases and thus is not a good a specific indicator of celiac.
Generally, IgA class AGA is more specific, but about 2% of celiac patients show selective IgA deficiency, and thus show negative results, even though they have celiac.
A positive IgG and IgA AGA gives a reported sensitivity of 96% to100% and specificity of 96% to 97%. Recent studies show Anti-reticulin antibodies (ARA) in people with celiac disease, but these appear to be nonspecific. In fact, taken alone, IgG ARA is largely ineffective. However, IgA ARA has sensitivity of 97% and a specificity of 98% in adults. These figures are much lower in children.
IgA class anti-endomysial antibody (EMA) and human jejunal antibody (JAB) have recently been identified as both sensitive and specific for celiac disease.
The antibody EMA, which reacts against endomysium reticulin fibers, has been found only in people with active celiac and not other diseases. As EMAs are associated with other diseases in children, they are a less accurate indicator of celiac in children than in adults.
Studies in children less than 2 years old with celiac disease have shown a steep fall in EMA sensitivity, so EMA appears even less useful than in children over 2 years of age.
Finally, since the EMA and JAB antibody tests may be negative in adults with celiac disease and IgA deficiency, they cannot be considered definitive for diagnosis of celiac disease.
A complete panel of antibody tests seems to be most accurate method of diagnosing celiac disease.
Taken together, a positive panel of IgG AGA, IgA AGA and EMA can predict the presence of celiac disease in 99.3% of patients. A negative panel of IgG AGA, IgA AGA and EMA can predict the absence of celiac in 99.6% of patients.
These antibodies tend to diminish or disappear when individuals maintain a gluten-free diet.
More than 90% of patients with celiac disease have genetic markers HLA DQalpha *0501, and HLA DQbeta *0201. Negative tests for these markers in conjunction with negative serum antibody tests suggest an absence of celiac disease. However, positive tests for the genetic markers do not necessarily mean that the patient has celiac disease. In conclusion, genetic markers can be used as a test to exclude celiac disease as a diagnosis.
Celiac Disease Biopsy
A diagnosis of celiac disease is generally confirmed through a biopsy, by looking for celiac associated damage to the small intestine.
One important fact is that intestinal biopsies are regularly obtained endoscopically from the duodenum and therefore provide no information regarding the extent of disease along the jejunum.
Flattening of the villi usually occurs first, and most severely, in the duodenum, as it the duodenum is the first part of the intestine to be exposed to gluten. Conversely, the villi of the jejunum, which receives much less exposure, are often asymptomatic, and nearly normal.
In most of these individuals, treatment with a gluten-free diet results in the return of all villous and crypt structures to normal or near normal.
Certain conditions, especially infection, can yield intestinal biopsy results that are similar to those of celiac disease, and it is important to consider and/or exclude these conditions when celiac disease is suspected.
Practice Guidelines for Treatment of Celiac Disease with an Aggressive Life-long Gluten-free Diet
As there is presently no cure for celiac disease, avoiding gluten is crucial. Practice guidelines call for a life-long gluten-free diet as the standard treatment for celiac disease. To manage the disease and prevent complications, its essential that patients avoid all foods that contain gluten. That means it is crucial for the patient to avoid all foods made with wheat, rye, or barley. This includes types of wheat like durum, farina, graham flour, and semolina. Also, bulgur, kamut, kasha, matzo meal, spelt and triticale. Examples of products that commonly contain these include breads, breading, batter, cereals, cooking and baking mixes, pasta, crackers, cookies, cakes, pies and gravies, among others.
It is also good practice for patients to avoid oats, at least during initial treatment stages, as the effects of oats on celiac patients are not fully understood, and contamination with wheat in processing is common. So, its a good practice when first adopting a gluten-free diet to eliminate oats, at least until symptoms subside, and their reintroduction into the diet can be fairly monitored and evaluated.
Another good practice is coaching celiac patients to avoid processed foods that may contain hidden gluten. Wheat flour is commonly used in many processed foods that one might never suspect. A few examples include candy bars, canned soup, canned meat, energy bars, ketchup, ice cream, instant coffee, lunchmeat, mustard, pastas, processed meat, sausages, and yogurt.
Also, gluten is also commonly found in many vitamins and cosmetics, such as lipstick, and in the production of many capsules and tablets, where wheat starch is a commonly used binding agent.
Obviously, patients must avoid beer made with barley or wheat (there are gluten-free beers), though wine, brandy, whiskey and other non-wheat or non-barley alcohols are okay.
Encourage patients to eat a diet rich in fish, fresh meats, rice, corn, soybean, potato, poultry, fruits and vegetables. Patients should also avoid milk and other dairy products, as it is common for patients with celiac disease to be lactose intolerant. Dairy products can often be slowly reintroduced into the diet over time with successful treatment.
It is also important for patients to learn to identify gluten-free foods. Because a gluten-free diet needs to be strictly followed, and because food ingredients may vary from place to place and even over time for a given product, it is important to always read the label.
For lists of gluten-free foods and products, and for specific advice on adopting, shaping and maintaining the gluten-free diet that is right for them, patients may wish to consult a registered dietitian who is experienced in teaching the gluten-free diet.
Most patients who remove gluten from their diets find that their symptoms improve as inflammation of the small intestine begins to subside, usually within several weeks. Many patients who adopt a gluten-free diet report an improvement within 48 hours.
Results of a gluten-free diet can be especially dramatic in children with celiac disease. Not only does their diarrhea and abdominal distress usually subside but, frequently, their behavior and growth rate are often markedly improved.
A reappearance of intestinal villi nearly always follows an improvement in symptoms.
In younger people, the villi may complete healing and re-growth in several months, while in older people, the process may take as long as two to three years.
In cases where nutritional deficiencies are severe, celiac patients may require vitamin and mineral supplements to help bring about a healthier vitamin profile: folic acid and B12 for patients with anemia due to folate or B12 deficiency; vitamin K for patients with an abnormal ProTime; calcium and vitamin D supplements for patients with low blood calcium levels or with osteoporosis. For all such cases, individuals should consult their health professional.
Skin lesions common in patients with dermatitis herpetiformis often improve with adherence to a gluten-free diet.
The Importance of Follow-up Testing for Celiac Patients on a Gluten-free Diet
Research indicates that only half of those patients who have had celiac disease for at least 20 years were following a strict gluten-free diet. Up to 30% of those patients showed evidence of bone loss and iron deficiency. These are but a few of the long-term consequences for celiac patients failing to follow a gluten-free diet.
Thus, it is important to conduct follow-up testing of celiac patients to determine the success of their gluten-free diets, and the progress of their treatment, and to make any necessary adjustments to each. Even done properly, with no accidental consumption of gluten, the elimination of gluten antibodies from the blood takes months. To estimate the treatments effectiveness, current guidelines call for a single serological testing after 3-6 months on a gluten-free diet.
For patients who are free of antibodies, and actively following a gluten-free diet, it is wise to consult a doctor if there is any recurrence of celiac-associated symptoms. First-degree relatives of celiac patients should have a repeat blood test every 2-3 years.
health writer who lives in San Francisco and is a frequent author of articles for Celiac.com.