Center of Excellence for Celiac Disease: Diagnosis

Celiac disease is a highly underdiagnosed condition.

Studies indicate a prevalence of 1% of the population, although only 10–15% of patients are diagnosed. Many of the rest may not exhibit clinical symptoms, but a significant portion of them suffer from chronic health problems.

Celiac disease is an autoimmune disorder consisting of an immune intolerance to the glutamine residues in gluten; it is characterized by chronic inflammation and atrophy of the villi in the proximal small intestine and manifests in genetically predisposed individuals; and is therefore more common among the children of people with celiac disease than in the general population.

As a result, the small intestine is unable to absorb nutrients, leading to various symptoms characteristic of this disease.

The course of this disease varies, and its progression depends primarily on diet.

Germano de Sousa HPV e Cancro do Colo do Útero

Celiac disease can occur at any age; it can begin in childhood or in adulthood, provided that gluten has been introduced into the diet.

The severity and consequences of intestinal damage vary from case to case and are sometimes mild.

The disease typically manifests during a child’s second year of life, as soon as they begin consuming gluten (baby food, bread, cookies, etc.).

The child begins to lose their appetite, fails to gain weight, and exhibits anorexia, loss of muscle mass, and hypotonia, accompanied by diarrhea—which may consist of pale, bulky, foul-smelling stools and abdominal distension (the belly becomes more prominent), and the child becomes sad and irritable. Edema may occur if hypoproteinemia is severe enough.

In older children, this can lead to growth retardation; various complications may also arise due to mineral and vitamin deficiencies, such as iron-deficiency anemia, dental defects, possible bone disorders due to vitamin D deficiency, bleeding due to vitamin K deficiency, itching and cramps due to calcium deficiency, and mood changes.

Sometimes there are cases in which the symptoms are different, with only repeated vomiting, abdominal pain of varying intensity, constipation, or simply growth delay with no apparent explanation.

Celiac disease generally manifests more severely in the early years of life, after which its severity tends to decrease.

In adults, symptoms include fatigue, abdominal cramps, bloating, diarrhea, constipation, flatulence, and anemia; many adults also experience dermatitis herpetiformis, reduced fertility or even infertility, recurrent miscarriages, and neurological changes.

There is no cure for celiac disease; a gluten-free diet must be followed for life.

Therefore, grains such as wheat, rye, barley, and oats must be eliminated from the diet.

Eliminating gluten from the diet allows intestinal damage to heal, enabling the intestine to return to normal function after a few months.

If gluten is ingested, even in small amounts, the atrophy of the intestinal villi returns and symptoms reappear.

It is extremely important that the diagnosis be made in a timely manner; only in this way can the patient’s quality of life be improved and the long-term risks of untreated disease be reduced.

When making the diagnosis, the characteristic signs and symptoms of the disease must be taken into account; the doctor should order blood tests, and a biopsy must be performed for definitive confirmation.

Serological markers for the diagnosis of celiac disease are:

Total IgA measurement to determine IgA deficiency (20% prevalence)
Anti-Deaminated Gliadin IgA (AGA IgA)
Anti-Deaminated Gliadin IgG Antibody (AGA IgG)
Anti-tissue transglutaminase IgA (tTG IgA)
Anti-tissue transglutaminase IgG (tTG IgG) (if IgA deficiency)
Anti-Endomysium Antibodies (IgA) (EMA IgA) – Higher Specificity
Anti-Endomysium Antibody (IgG) (if IgA deficiency)

Anti-tTG IgA/IgG Antibodies (in cases of IgA deficiency) are highly sensitive and specific for the diagnosis of celiac disease.

If the result is positive, it must always be confirmed by anti-endomysial antibodies (IgA/IgA), as this is the most specific test for diagnosing celiac disease.

Seroconversion to tTG IgA generally occurs only after 4–5 years of age; therefore, both IgA and IgG antibodies should be tested. On the other hand, transiently elevated levels of tTG IgA may be found in children without celiac disease, so these patients should be monitored.

The risk of celiac disease is approximately 10–20 times higher in patients with IgA deficiency than in the general population.

After diagnosis of the disease, it is important to ensure ongoing surveillance through regular monitoring tests for patients following a gluten-free diet.

The IgA/IgG (in cases of IgA deficiency) anti-tissue transglutaminase (tTG) antibody is very useful in monitoring treatment, in addition to its role in diagnosis. Its levels may normalize within 6–12 months after starting the diet. tTG levels do not correlate with the repair of the intestinal mucosa.
Anti-gliadin (AGA) IgA/IgG antibodies (if IgA-deficient) are useful for monitoring treatment. The fact that these antibodies can be found in healthy individuals limits their diagnostic value. Their levels may return to normal approximately 3 to 9 months after starting the diet. For monitoring patients with IgA deficiency, IgG is more recommended than tTG IgG.

Before performing the serological test, several considerations should be taken into account:

Serological tests for celiac disease should not be used in children before gluten has been introduced into their diet.
Any test for celiac disease should be performed only if the person continues to follow a gluten-containing diet during the diagnostic process (serological tests and biopsy if necessary).
It is important that the patient not start a gluten-free diet until the diagnosis is confirmed by an intestinal biopsy, or alternatively, if the serological tests are negative and clinical suspicion is very high, an HLA-DQ2/DQ8 test should be performed; if negative, it has a Negative Predictive Value (NPV) of 100%, meaning the patient does not have celiac disease and should not undergo a biopsy.

HLA-DQ2/DQ8 Negative Predictive Value of 100%