How can celiac disease be diagnosed?

Celiac disease is a chronic autoimmune condition that occurs in genetically predisposed individuals when they consume gluten. The only way to treat celiac disease is to follow a gluten-free diet for life. However, before treatment can begin, an accurate diagnosis is necessary.

Diagnosing celiac disease can be a long and complicated process, as symptoms can vary widely from person to person, and some patients may have no symptoms at all. In addition, it can easily be confused with other conditions and may be overlooked by physicians, especially in primary health care.

It is a disease that many more people than estimated may have it without knowing it. If a person suspects that he or she may have the disease, he or she should see a specialist, in this case a gastroenterologist.

To make an accurate diagnosis it is necessary to take into account the patient's history and symptoms, the results of blood screening tests, genetic testing and intestinal biopsy. In addition to follow up during the gluten-free diet to evaluate the clinical and histological evolution of the person.

It is not always necessary to do all the tests, but none by itself confirms the diagnosis. Despite a positive diagnosis, people with this disease can lead a long and healthy life as long as they comply with the only effective treatment available today, a strict gluten-free diet. The following are the steps involved in the diagnosis of celiac disease.

Medical history and physical examination

At this stage, the physician will review the patient's medical history to confirm if he/she belongs to any risk group associated with celiac disease such as: Diabetes Mellitus type 1, Lactose Intolerance, Autoimmune Thyroiditis, or Down's Syndrome. Or if a close family member has been diagnosed with celiac disease.

In addition, he or she will perform a physical examination to evaluate any possible signs or symptoms of celiac disease. These symptoms may be digestive or non-digestive. The most common include chronic diarrhea, weight loss, fatigue, iron deficiency anemia and abdominal pain. But it can also present constipation, skin rash, headache, joint pain, osteoporosis, depression, anxiety, infertility, among others.

The specialist will not only be interested in the symptoms, when they started and how they have evolved. He/she will also be interested in the patient's lifestyle, as well as recent changes and medications taken.

Blood screening tests

If the physician suspects that the patient may have celiac disease, screening tests may be performed to confirm the diagnosis. Early detection is important because untreated celiac disease can lead to serious complications, such as osteoporosis, infertility and bowel cancer.

In addition to standard blood tests, where anemia, decreased platelets and leukocytes, elevated liver enzymes, and so on can be detected. More specific tests are performed that detect antibodies in blood such as:

• Anti-gliadin antibodies (AGA).

• Anti-tissue transglutaminase antibodies (tTG)

• Anti-endomysial antibodies (EMA).

These serological tests may indicate the presence of celiac disease if antibodies to gluten are found, but they are not definitive. Some celiac patients do not have elevated antibodies and may have seronegative celiac disease. If the suspicion is high, further testing is necessary.

It is very important that the person has not stopped eating gluten before the blood tests are performed, as this may interfere with the results. However, in cases where a person has already eliminated gluten from their diet and celiac disease is suspected, genetic testing can be performed to determine the presence of genes associated with the disease.

Genetic testing

This test is used to confirm a person's genetic predisposition to develop the disease. Two genes related to celiac disease have been identified so far, HLA DQ2 and HLA DQ8. But their presence alone is not a confirmation of the disease.

In the case of being positive, it does not mean that you have the disease. More than 30% of the population shares this characteristic, and only a minimum percentage develops the disease. If these variants are present, but the antibody test was negative, an intestinal biopsy is recommended to confirm the diagnosis. However, if the result is negative, the possibility of celiac disease is practically ruled out.

Intestinal biopsy

This refers to obtaining and analyzing samples from the small intestine by endoscopy. The samples are examined under a microscope to look for characteristic changes in the intestinal mucosa that indicate celiac disease.

It is the gold standard of celiac disease diagnosis as it can accurately determine if there are signs of damage to the small intestine and the extent of damage.

Intestinal biopsy is a relatively simple and safe procedure, but there may be some risks, such as bleeding or infection. It is important for the patient to discuss any concerns or questions with their physician.

The Gluten-Free Diet (GFD)

Even with all of these tests, another step in the diagnosis may be to start a gluten-free diet and assess the patient's response. Usually by 6 months there should be a clear improvement in quality of life and relief or elimination of symptoms. Damage to the small intestine takes a little longer to subside.