Deamidated gliadin peptide (DGP) antibodies (anti-DGP), IgA or IgG — may be used in some people with suspected celiac disease who are negative for anti-tTG, especially children younger than 2 years old. DGP IgG testing along with anti-tTG IgG is recommended by the American College of Gastroenterology for people who have low IgA or IgA deficiency. If the anti-DGP test is positive, it may be used to monitor celiac disease.

Celiac disease is a gluten enteropathy occurring in both children and adults. The disease is probably underdiagnosed in that it may affect as much as 1% of the population in the United States. The condition is characterized by a sensitivity to gluten (found in wheat, barley, and rye) that causes inflammation and atrophy of the villi of the small intestine, malabsorption, etc. This sensitivity to gluten may also be seen in dermatitis herpetiformis. Strict avoidance of gluten in the diet will control disease activity, and antibodies to serum markers will disappear with time.

To confirm a diagnosis of celiac disease, a biopsy of the small intestine is examined to detect damage to the intestinal villi. However, given the invasive nature and cost of a biopsy, antibody tests are often used to identify those individuals with high probability of having celiac disease.

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Celiac disease tests are ordered when someone has signs and symptoms suggesting celiac disease, malnutrition, and/or malabsorption. The symptoms are often nonspecific and variable, making the disease difficult to spot. The symptoms may, for a time, be mild and go unnoticed and then progressively worsen or occur sporadically. The condition can affect different parts of the body.

Digestive signs and symptoms may include:

- Abdominal pain and distension
- Bloody stool
- Chronic diarrhea or constipation
- Flatulence
- Greasy, foul-smelling stools
- Vomiting
 
Other signs and symptoms may include:

- Iron-deficiency anemia that does not respond to iron supplements
- Easy bruising and/or bleeding
- Bone and joint pain
- Defects in dental enamel
- Fatigue, weakness
- Mouth ulcers
- Weight loss
- In adults, infertility, osteoporosis
 
In children, celiac disease tests may be ordered when a child exhibits:

- Digestive tract symptoms
- Delayed development
- Short stature
- Failure to thrive
 
Many people with celiac disease have dermatitis herpetiformis, a disease that causes itchy blisters on the skin. There is also an increased risk for developing intestinal lymphoma, a form of cancer.

One or more antibody tests may be ordered when someone with celiac disease has been on a gluten-free diet for a period of time. This is done to verify that antibody levels have decreased and to verify that the diet has been effective in reversing the intestinal lining damage (this is sometimes still confirmed with a second biopsy).

Asymptomatic people may be tested if they have a close relative such as a parent or sibling with celiac disease, but celiac disease testing is not recommended at this time as a screen for the general population.