Differential diagnosis of celiac disease.

Interpretation of celiac disease (CD) screening test results can be complicated. The physician trained in the diagnosis and treatment of celiac disease will need to make a differential diagnosis to rule out other conditions that may share similar clinical and laboratory findings or symptoms.

Different diseases may share one or more symptoms. The physician will make a list of possible conditions based on symptoms, medical history, family history, medications taken, lifestyle, and physical examination.

After this, a process of ruling out suspected diseases begins, in which relevant tests are performed and their results are interpreted until the cause is found and treatment is initiated.

Differential diagnosis of celiac disease with other gastrointestinal conditions is important because symptoms may be similar in several conditions, which can lead to misdiagnosis and delay in appropriate treatment.

Some of the gastrointestinal conditions that may have similar symptoms to celiac disease include:

• Non-celiac gluten sensitivity (NCGS): NCGS is characterized by symptoms similar to celiac disease, but without the presence of damage to the small intestine. Non-celiac gluten sensitivity can be difficult to diagnose due to the lack of specific biomarkers. Symptoms of NCGS include diarrhea, abdominal pain, bloating, fatigue and depression.

• Inflammatory bowel disease (IBD): IBD is a general term that refers to a group of chronic inflammatory bowel disorders, such as Crohn's disease and ulcerative colitis. IBD can present with symptoms similar to those of celiac disease, such as abdominal pain, diarrhea and weight loss. However, in IBD there may also be blood in the stool, fever and anemia.

• Irritable bowel syndrome (IBS): IBS is a functional bowel disorder characterized by recurrent abdominal pain, bloating and altered bowel movements. The symptoms of IBS can be similar to those of celiac disease, but there is no damage to the small intestine. IBS can be difficult to diagnose, as there are no specific tests for this condition.

• Food allergy: A food allergy is an immune system response to a specific food. The symptoms of a food allergy can be similar to those of celiac disease, such as nausea, diarrhea, abdominal pain, rashes and vomiting. However, in a food allergy there may also be congestion in the nose and eyes, breathing problems, hives or swelling. Food allergy also does not destroy the wall of the intestine.

To differentiate celiac disease from other gastrointestinal conditions, various diagnostic tests and analyses are performed. The physician may order blood tests, such as measurement of anti-tissue transglutaminase antibodies (anti-tTG) and anti-endomysial antibodies (anti-EMA), which are usually elevated in celiac disease. An endoscopy with intestinal biopsy may also be performed to evaluate damage to the small intestine and to rule out other conditions that may present with similar symptoms.

In addition, the physician may test for food allergies or examine bowel function through intestinal transit or motility tests.