Diagnosing celiac disease (gluten intolerance)

Many people suffer from stomach pain and discomfort, and though people can get "used to" these symptoms, it's important to take them seriously and to see a medical professional.

Celiac disease can only be diagnosed by a doctor. Under no circumstances should a patient alter their diet independently based only on a suspicion, as a true diagnosis can only occur after a doctor's symptom evaluation and testing. 

Blood test for suspected Gluten Intolerance

The first step when a doctor suspects celiac disease is a blood test. It's important to know that changing your diet before taking the blood test will lead to an inaccurate result, as it’s possible that the blood antibodies will be below the determination threshold. 

If the blood test delivers typical antibodies (tissue transglutaminase IgA antibodies or endomysium IgA antibodies) in an increased concentration, the small intestine is then biopsied.

Biopsy of the small intestine

This biopsy is performed by means of gastroscopy, in which a small piece of the small intestinal mucous membrane is removed and microscopically examined. These microscopic images show clearly whether the small intestine is inflamed and the intestinal villi are re-formed. Depending on the degree of damage to the intestinal villi, they are classified using the Marsh Criteria – as defined by pathologist Michael N. Marsh. The classifications range from Marsh Type 0 (no abnormalities) to Marsh Type 3c, a completely flattened mucosal surface.

It is important that the affected individual continue consuming gluten until the time of the biopsy. In most cases, the intestinal mucous membranes are repaired rapidly. In a celiac patient who is already gluten-free, the pathologist may not be able to provide evidence of the damaged intestinal wall.

Unnecessary diagnostic procedures for celiac disease

For children, a biopsy is only performed in severe cases in which the symptoms are clear and the specific antibodies are at least 10 times the upper limit.

A genetic test cannot absolutely diagnose celiac, but it can rule it out. Those who suffer from celiac disease carry a certain gene variant, HLA-DQ2 or HLA-DQ8. However, in addition to individuals with celiac, about 25 percent of the population also carries this gene. A genetic test can therefore show that a patient is a HLA-DQ2 or HLA-DQ8 carrier and thus has the genetic prerequisite to develop celiac. However, such a result does not defninitively indicate whether the person is actually suffering from celiac disease. Conversely, this means that a genetic test may potentially rule out celiac. That is, if the results show that the patient does not carry HLA-DQ2 or HLA-DQ8, then the genetic prerequisite for celiac (gluten intolerance) has not been met.

It's important to note that rapid tests, which are intended to provide clarity when suspected of food intolerances, as well as saliva and stool tests, are generally regarded as unreliable diagnostic methods for celiac disease.

Further reading:

What is celiac disease (gluten intolerance)?

Symptoms and concurrent disorders of celiac disease (gluten intolerance)

Treatment for celiac disease (gluten intolerance)