What Is Celiac Disease?

Diagnosis of Celiac Disease

According to the Statement on Celiac Disease prepared by the National Institutes of Health Consensus Development Conference, a diagnosis of celiac disease requires several steps:

1. Serologic testing. If a physician suspects that a patient has celiac disease, the first step in the diagnostic process is often a simple blood test. Serologic tests are useful for diagnosing celiac disease. They measure blood levels of antibodies that are found in above-normal levels in persons with celiac disease. The serologic tests that are currently considered the best are the immunoglobulin A antihuman tissue transglutaminase (IgA tTG) and the immunoglobulin A endomysial antibody immunofluorescence (IgA EMA).
2. Intestinal biopsy. If the results of the serologic tests are consistent with what would be found in celiac disease, the next step in the diagnostic process is an intestinal biopsy, in which tissue samples from the mucosa of the upper end (duodenum) of the small intestine are examined under a microscope for abnormalities consistent with celiac disease. Biopsy samples are collected during an upper endoscopy, an outpatient procedure performed by a gastroenterologist. The most important abnormality from the standpoint of diagnosing celiac disease is villous atrophy, or shortening of the villi that line the mucosa of the small intestine.
3. Gluten-free diet. If findings of the serologic tests and/or intestinal biopsy are consistent with what would be seen in celiac disease, the third step in the diagnostic process is to have the patient follow a gluten-free diet. If, together with positive serological and/or biopsy findings, the gluten-free diet reduces (and eventually resolves) any gastrointestinal symptoms the patient was experiencing, a definitive diagnosis of celiac disease can be made.

Treatment of Celiac Disease

The only available treatment for celiac disease is a gluten-free diet. This is so fundamental and important that it bears repeating with emphasis: The only treatment for celiac disease is a gluten-free diet.

The only controversy surrounding treatment is what exactly constitutes a gluten-free diet.  In the United States, a gluten-free diet is generally defined as a diet that does not include protein from wheat, barley, rye, and possibly oats.

Why It's Important to Follow a Gluten-Free Diet

When a person with celiac disease stops eating wheat, barley, and rye, the proteins that used to trigger an immune system reaction are no longer present in the body. Removing these harmful grains from the diet not only prevents further damage to the small intestinal mucosa but also allows it to heal. Intestinal villi grow back, and the body absorbs more nutrients. Any gastrointestinal symptoms that were caused by malabsorption begin to decrease, and it becomes possible to treat vitamin and mineral deficiencies that may have occurred.

Science Class

You don't need to understand cereal chemistry to follow a gluten-free diet, but you may find it helpful to understand the terms gluten and prolamin.

Gluten

From the standpoint of celiac disease, the term gluten is used to describe proteins found in wheat, barley, and rye that must not be eaten in a gluten-free diet. Strictly speaking, however, gluten is a protein found only in wheat. It is made up of groups of proteins (of two types, glutelins and prolamins), including the glutelin glutenin and the prolamin gliadin. Gluten is responsible for the "elasticity" of baked goods made with wheat flour.

The term gluten is sometimes used in a more general sense to describe proteins (glutelins and prolamins) found in many cereal grains. For example, you may hear or see references to corn gluten or rice gluten, both of which are fine for you to eat.

Prolamins

Prolamins are storage proteins found in many cereal grain foods. They are called storage proteins because they are a source of nutrients for developing plants. The prolamins of wheat, barley, and rye, termed gliadin, hordein, and secalin respectively, contain the specific amino acid sequences harmful to persons with celiac disease. However, not all prolamins are harmful. For example, the corn prolamin zein and the rice prolamin orzenin do not contain harmful amino acid sequences, so they do not trigger immune responses in persons with celiac disease.

It is important to note that while gliadin is generally implicated as the harmful fraction of gluten, glutenin also may contain amino acid sequences harmful to persons with celiac disease.

Dermatitis Herpetiformis

Dermatitis herpetiformis (DH) is a form of celiac disease involving the skin. If you have DH, you will develop extremely itchy, raised blistering skin lesions if you eat protein from wheat, barley, and rye. These lesions may occur on the outer surface of the elbows, knees, shoulders, and buttocks and are evenly distributed on both sides of the body. In most cases, the mucosa of the small intestine also is damaged, although you may not experience any gastrointestinal symptoms.

DH is diagnosed using a biopsy of the skin. If the biopsy reveals a buildup of immunoglobulin A antibodies, a diagnosis of DH can be made. Dermatitis herpetiformis is treated with a gluten-free diet as well as the medications dapsone and sulfapyri-dine for the skin lesions. The use of medication alone will resolve the skin but not the intestinal lesions.