Celiac disease is an inflammatory digestive disease that damages the small intestine and it is caused by gluten intolerance in people genetically susceptible.
In some people, gluten may damage the small intestine and interfere with the absorption of nutrients. Gluten is present in cereals such as wheat, rye, or barley.
When someone with celiac disease eat foods containing gluten, the immune system response is activated. The activation of the immune system causes the inflammation of the small intestine and the inability to absorb nutrients from foods. For this reason, celiac disease is also considered an autoimmune disease.
Gluten is a group of proteins present in many cereal grains. Gluten is composed of two types of proteins called prolamins (soluble in alcohol) and glutelins (insoluble in alcohol).
Prolamins and glutelins are present in cereal grains. Wheat, for example, owns two types of proteins called gliadin (a type of prolamin) and glutenin (a type of glutelin).
The different type of prolamins present in cereal grains are:
| Cereal | Type of Prolamin | Content % |
| Wheat | Gliadin | 69% |
| Rye | Secalin | 30-50% |
| Oats | Avenin | 16% |
| Barley | Hordein | 46-52% |
| Millet | Panicin | 40% |
| Corn | Zein | 55% |
| Rice | Orzenin | 5% |
| Sorghum | Kafirin | 52% |
Many kids are diagnosed with celiac disease when they around two years old, after wheat is introduced into the diet. In adults, the average age of diagnosis is between 30 and 40 years old.
The intestinal villi allow the body the absorption of food and nutrients. Villi are small finger-like projections inside the small intestines. In celiac disease, these villi become flat and as a consequence the nutrient absorption decrease. The atrophy of the villi defines how the disease affects each person.
In many cases, the disease is asymptomatic. If there is any symptom the most common ones are:
Abdominal pain is usually present followed by flatulence and a distended abdomen.
Anemia is caused by the malabsorption of iron, folic acid, and/or vitamin B12.
In some case, arthritis is also present. Common symptoms of arthritis are joint pain, joint stiffness, and weakness.
Poor absorption may result in bone diseases (osteoporosis, bone fractures, osteomalacia) and tetany (involuntary muscle spasms).
There may be also symptoms related to the nervous system such as burning tingling or numbness in hands and feet, inability to stand upright, muscle weakness, irritability and memory impairment.
In addition, around 10% of people with celiac disease suffer from dermatitis herpetiformis and around 85% of people with dermatitis herpetiformis has celiac disease at the same time.
Celiac disease is a genetic and hereditary disease and therefore there is a family predisposition. The most common genes implicated are the HLA-DQ2 gene (related to 90% of the cases) and the HLA-DQ8 gene (related to 5% of the cases). Both genes are located on chromosome 6.
Despite the genetic predisposition, the conditions that may trigger the disease (the autoimmune response) are unclear.
The main mechanisms involved in the gluten intolerance are:
There are three different types of celiac disease with the following clinical features:
Celiac disease is diagnosed looking for antibodies in the blood, intestinal biopsy and by the explained symptoms.
The biopsy is the removal of a tiny piece of tissue from intestine to study it under the microscope. The biopsy is usually taken from the duodenum (first section of the small intestine), although biopsy from the jejunum (middle section of the small intestine) is usually more specific.
The biopsy is a useful screen to diagnose celiac disease but sometimes it is necessary to repeat it to avoid false positives by intestinal infection or lactose intolerance.
Some patients may have a normal biopsy when the disease is inactive or the disease is in remission, although they remain very sensitive to some types of prolamins.
Although a biopsy is necessary to confirm the diagnosis, the most important test for gluten intolerance is the remission of symptoms when cereals are excluded from the diet for 3-6 weeks.
Many serology tests may help in the diagnosis by detecting antibodies in the blood. These tests have a high sensitivity (correctly detection of patients with the disease) and they are very specific (they do not appear in healthy people).
The basic screening test is the detection of IgA anti-tissue transglutaminase (anti-tTG) antibodies. If these antibodies are detected in the blood, the probability of suffering from celiac disease is very high (specificity is more than 95%). In people with IgA deficiency, an anti-tTG IgG assay is recommended.
Besides, other additional serology tests may be performed:
All these antibodies usually show a negative result with a gluten-free diet. They are also helpful to follow-up with intestinal symptoms, but not extraintestinal symptoms.
The only treatment for celiac disease is to follow a gluten-free diet.
After two weeks of a gluten-free diet, in most cases there is an improvement.
Gluten is present in any product containing wheat, barley, oats, or rye. Therefore, the following foods should not be eaten:
However, in many supermarkets, you can find gluten-free alternatives of these foods.
If symptoms do not improve, it may be because the diet is not adequate or because there are lymphomatous complications.
In asymptomatic patients, gluten-free diet is also recommended because the disease worse when the diet is broken. Besides, the incidence of lymphoma and adenocarcinoma increases when intestinal inflammation is present.
Celiac disease affects every system in the body, so many conditions related to gluten intolerance are prone to be developed:
These diseases are not always related to bowel disorders.
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