INTRODUCTION
Celiac disease is a condition in which the immune system responds abnormally to a protein called gluten, which can cause damage to the lining of the small intestine. Gluten is found in wheat, rye, barley, and a multitude of prepared foods. Celiac disease is also known as gluten sensitive enteropathy ("enter-OH-pathy"), celiac sprue, and nontropical 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 necessary 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 and it affects both genders.
SIGNS AND SYMPTOMS
The signs and symptoms of malabsorption vary from one person to another. In its mildest form, there may be no symptoms whatsoever. Even in people who have no symptoms, there may be evidence of malabsorption on laboratory testing. As an example, a low blood count may develop as a result of decreased iron absorption.
Others people have more bothersome symptoms, including diarrhea, weight loss, abdominal discomfort, excessive gas, osteoporosis, and other signs and symptoms due to deficiencies of specific vitamins and nutrients.
Some conditions are more common in people with celiac disease, including:
CAUSES
It is not clear why some people develop celiac disease. Genetic factors are clearly important since celiac disease occurs primarily in certain groups of people, specifically whites of northern European ancestry. People who inherit specific genes that regulate the immune response (HLA DQ2 and HLA DQ8) have a higher risk of celiac disease than people without these genes. However, other factors are also important since only a minority of individuals who are DQ2 or DQ8 positive actually develop celiac disease.
DIAGNOSIS
Celiac disease can be difficult to diagnose because the signs and symptoms are similar to other conditions. Fortunately, testing is available that can distinguish celiac disease from other disorders.
Blood tests
A blood test is available that determines the blood level of antibodies (proteins) that become elevated in people with celiac disease:
- IgA endomysial antibody (IgA EMA)
- IgA tissue transglutaminase antibody (IgA tTG)
Before having these tests, it is important to continue eating a normal diet, including foods that contain gluten. Avoiding or eliminating gluten could cause the antibody levels to normalize. Over 90 percent of people with untreated celiac disease have elevated antibody levels, while these levels are rarely elevated in those without celiac disease.
Small intestine biopsy
If the blood tests are positive, the diagnosis must be confirmed by examining a small sample of the intestinal lining with a microscope. The sample (called a biopsy) is usually collected during an upper endoscopy, a test that involves swallowing a small flexible instrument with a camera. The camera allows a physician to examine the upper part of the gastrointestinal system and remove a small piece (biopsy) of the small intestine. The biopsy is not painful. (
See "Patient information: Upper endoscopy"
).
In people with celiac disease, the lining of the small intestine has a unique appear when viewed with a microscope. Normally, the lining has distinct finger-like structures, which are called villi. Villi allow the small intestine to absorb nutrients. The villi become flattened in people with celiac disease (
show histology
). Once gluten is removed from the diet, the villi can resume a normal growth pattern.
Some clinicians recommend repeating the biopsy after gluten has been eliminated from the diet for a few months to see that the villi have regrown. If the diagnosis is still in doubt after a period of treatment with a gluten free diet, it may be necessary to resume gluten to see if the villi become flattened again.
One way to determine if the gluten free diet is working is to monitor the levels of endomysial and tissue transglutaminase antibodies in the blood. The levels should decline on the gluten-free diet, which indicates that the diet has been effective.
Latent celiac disease
At present, people with a positive IgA endomyseal antibody test and a normal small bowel biopsy are considered to be latent celiacs. Such patients are not usually advised to follow a gluten-free diet. However, ongoing monitoring is recommended and a repeat biopsy may be needed if symptoms develop. Multiple intestinal biopsies are recommended since the abnormality can be patchy.
Testing for malabsorption
Patients with celiac disease should be tested for nutritional deficiencies. Common tests include a blood count to detect low levels of iron, folic acid, or vitamin B12, calcium, vitamin D, or vitamin K.
Many clinicians recommend specific testing for bone loss. One method involves using a DEXA (dual energy x-ray absorptiometry) scan to measures the density of bone. The test is not painful and is similar to having an x-ray. People who have developed significant bone loss may require treatment to stop bone loss or encourage new bone growth. (
See "Patient information: Osteoporosis causes, diagnosis, and screening"
, section on diagnosis).
COMPLICATIONS
Refractory sprue
People with untreated celiac disease can develop anemia, bone loss, and other consequences of malabsorption. A small percentage of patients develop intestinal symptoms that do not improve despite use of a gluten-free diet. In other cases, intestinal symptoms initially improve with dietary changes but then return. This condition is called refractory sprue. The cause of refractory sprue is not know. Treatment involves medications that suppress the immune system's abnormal response (eg, steroids).
Ulcerative jejunitis
Patients with refractory sprue who do not improve with steroids (glucocorticoids) may have a condition known as ulcerative jejunitis. This 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 usually involves an attempt to surgically removing the ulcerated area.
Lymphoma
Cancer of the intestinal lymph system (lymphoma) is an uncommon complication of celiac disease. Avoiding gluten can usually prevent this complication.
TREATMENT
Gluten free diet
The cornerstone of treatment for celiac disease is complete elimination of gluten from the diet. Patients who are malnourished because of the disease may also need nutritional supplements.
Maintaining a gluten-free diet can be a difficult task that requires major lifestyle adjustments. Gluten is contained in the most commonly consumed grains in the Western world (wheat, rye, and barley) and is included as an additive in a large number of prepared foods (
show table 1
). Strict gluten avoidance is recommended since even small amounts can aggravate the disease.
In general:
- Foods containing wheat, rye, and barley should be avoided.
- Soybean or tapioca flours, rice, corn, buckwheat, and potatoes are safe.
- Read labels on prepared foods and condiments carefully, paying particular attention to additives such as stabilizers or emulsifiers that may contain gluten.
- Dairy products may not be well tolerated initially since many patients with celiac disease can have secondary lactose intolerance. As a result, lactose-containing products should initially be avoided in patients whose symptoms appear to be worsened by them.
- Oats do not appear to be harmful. However, oats should be avoided unless the package specifically indicates that the product is gluten free and was processed in a gluten free facility
Consultation with an experienced celiac nutritionist is recommended for detailed guidance and written information. In addition, a number of helpful resources are available. (
See "
Where to get more information" below
).
Fortunately, life on a gluten free-diet has become increasingly easier due to the popularity of gluten-free foods. Excellent gluten-free substitutes for traditional gluten-containing foods are now widely available (
show table 2
).
Is gluten avoidance really necessary?
People who have no symptoms of celiac disease often find it difficult to follow a strict gluten-free diet. Indeed, some healthcare providers have questioned the need for a gluten-free diet in this population. However, certain factors support a gluten-free diet, even in those without symptoms:
- Strictly following a gluten-free diet sometimes helps a person to feel more energetic and have an improved sense of health and well being.
- Despite feeling well, some patients with celiac disease have vitamin or nutrient deficiencies. These deficiencies often cause symptoms if gluten is not eliminated (such as anemia due to iron deficiency or bone loss due to vitamin D deficiency).
- Untreated celiac disease can increase the risk of certain types of gastrointestinal cancer. This risk can be reduced by adhering to a gluten-free diet.
- Pregnant women with untreated celiac disease are at increased risk for having a newborn who is smaller than normal.
Skin conditions
Celiac disease is associated with a number of skin disorders, of which dermatitis herpetiformis is the most common (
show table 2
). 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 (
show picture 1
) and (
show picture 2
).
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 several weeks to see significant improvement. In the mean time, an oral medication called dapsone may be recommended.
IMPLICATIONS FOR THE FAMILY
Eliminating gluten requires a major lifestyle change for the person who is affected by celiac disease as well as their family. However, with time and practice, it becomes easier to know which foods and ingredients contain gluten and what alternatives are available. Eating out can be challenging initially, although some restaurants offer a gluten free menu.
Families also need to be aware of their increased risk of celiac disease. Thus, first-degree relatives (parents, brothers, sisters, children) of a person with celiac disease should consider being tested, especially if there are any signs or symptoms of the condition. Testing is typically done with a blood antibody test, as described above (
see "Blood tests" above
).