Celiac Disease & Food Intolerances

Diagnosing Celiac Disease

It's estimated that more than 2 million people nationwide have celiac disease but have not been diagnosed.

While celiac disease primarily affects the gastrointestinal tract, it’s now recognized that the condition can affect other organ systems without showing noticeable gastrointestinal symptoms. This makes diagnosing celiac disease challenging.

Several blood tests are available to screen for celiac disease. The main test used for screening is the tTG-IgA test. Celiac disease blood tests measure for certain antibodies:

• IgA tissue transglutaminase (tTG) antibody
• Deamidated gliadin peptide (DGP) antibodies (IgA and IgG)
• IgA anti-endomysial antibody (used only on occasion)

If the test results are positive, or if the clinical picture suggests celiac disease, an upper endoscopy is performed to get a biopsy from the first part of the small intestine (duodenum).

While a blood test can help detect celiac disease, an endoscopic biopsy is the only way to confirm a definite diagnosis. Up to 10 percent people with celiac disease eating gluten have a "false" normal level of tTG IgA. So if you have pronounced symptoms yet your antibody test results indicate that you do not have celiac disease, an endoscopy and biopsy may be still be performed.

Why You Need A Professional Diagnosis

Celiac disease is not the same as a wheat allergy or gluten sensitivity without intestinal damage (non-celiac gluten sensitivity). The hereditary nature of celiac disease and the risk of nutritional deficiencies, other autoimmune diseases and GI cancers make it important to be properly diagnosed.

Prior to Celiac Disease Diagnosis

It is recommended not to start a gluten-free diet before you are diagnosed. The damage to the small intestine that is caused by gluten in people with celiac disease is reversible, and eliminating gluten from the diet before the biopsy is performed can interfere with obtaining accurate test results. Similarly, the antibody levels will decline once a gluten-free diet is started, making the blood tests less accurate in diagnosing celiac disease.

However, the biopsy can take well over a year or two before it returns to normal, so it is recommended that a biopsy is obtained soon after a patient on a gluten-free diet sees the physician.

Conditions That Can Mimic Celiac Disease

There are other digestive conditions that can cause symptoms from eating wheat and other grains and starches. These conditions are treated differently than celiac disease.

Non-Celiac Gluten Sensitivity

Non-celiac gluten sensitivity (NCGS) is a condition or syndrome that causes digestive symptoms that appear like celiac disease. However, NCGS does not cause intestinal damage or anemia, and the IgA celiac disease antibodies (TTG IgA and DGP IgA) are not typically elevated.

Patients with NCGS are often extremely sensitive to small amounts of gluten. The causes of NCGS are unknown and there are no diagnostic tests that can confirm the diagnosis of this condition.

The absence of the so-called celiac disease susceptibility HLA DQ genes rules out celiac disease and can suggest NCGS in patients with symptoms of celiac disease.

Wheat Starch Intolerance

Another cause of wheat or gluten sensitivity is wheat starch intolerance.

Wheat is made up of proteins (gluten) and carbohydrates (starch) which are found together in baked goods and other wheat products. Some individuals who are intolerant of or sensitive to wheat, like those with irritable bowel syndrome (IBS), are reacting to wheat starch, which can be fermented by bacteria in the intestines (the microbiome). 

If you have IBS and are sensitive to fermentable sugars and starches, you may have symptoms such as:

• Belly bloating
• Altered bowel habits
• Excessive gas
• Other digestive complaints

Help With Low FODMAP Diet

A low FODMAP diet can be difficult to follow. UC San Diego gastrointestinal experts can help you with FODMAP and other food intolerances.

People with wheat starch intolerance and IBS may alleviate symptoms with a low FODMAP diet. A low FODMAP diet consists of avoiding or limiting intake of certain carbohydrates that can be found in many natural and processed foods:

• Fructose
• Oligosaccharides
• Disaccharides
• Monosaccharides
• Polyols

Small Intestinal Bacterial Overgrowth (SIBO)

SIBO is another cause of intolerance of wheat and other starches due to the overgrowth of friendly bacteria in the small intestine.

SIBO can cause several digestive problems including:

• Food intolerances
• Diarrhea
• Altered bowel habits
• Abdominal pain or discomfort
• Abdominal bloating
• Excessive flatulence

In more severe cases, you may experience weight loss, anemia and nutritional deficiencies. The more severe forms of SIBO typically occur in elderly people, after gastrointestinal surgery, and in those who have altered motor function of the digestive tract. 

However, SIBO can occur in individuals who have a seemingly normal digestive tract, as well as those with IBS, celiac disease, and inflammatory bowel diseases (IBD).

Celiac Disease Treatment

Currently, treatment for celiac disease involves following a lifelong gluten-free diet. This means strictly avoiding:

• Wheat
• Barley and rye
• Foods, drinks and medications that contain gluten.

While maintaining a gluten-free diet can be challenging, it is important to restoring your health and improving quality of life.

Our team includes dietitians who provide tailored nutritional counseling to help people with celiac disease and other food sensitivities find foods that are satisfying and healthy. They work closely to provide you with:

• Recipes
• Tips for dining out
• Information on staying gluten-free
• Identifying hidden sources of gluten 

Our dietitians are also experts in other causes of food intolerances and treatments, including the low FODMAP diet. They will work with you to identify which foods may be the cause of your symptoms and make sure your modified diet is nutritionally balanced.