Introductory Chapter: Celiac Disease – An Overview

1. Introduction

Celiac disease (CD) is a multisystemic autoimmune-based process, caused by the ingestion of foods containing gluten and related prolamins, which affects genetically susceptible individuals, and is characterized by the presence of a variable combination of various gluten-dependent clinical manifestations, CD-specific antibodies, presence of compatible genetic markers of susceptibility (HLA, DQ2, or DQ8 haplotypes), and enteropathy. The most frequent pathological finding is the presence of chronic inflammation at the small intestine. The estimated average prevalence is around 1%, worldwide, being more frequent in women, with a 2:1 ratio. This definition was updated by the ESPGHAN, European Society for Pediatric Gastroenterology, Hepatology and Nutrition in 2012 [1].

Around 50% of all celiac patients remain undiagnosed for a long time. However, the recognition of other atypical forms of presentation, such as oligo and asymptomatic, combined with greater and better use of the complementary tests available, has made it possible to reveal the existence of different types of CD.

2. Clinical presentations

1. Symptomatic: The symptoms are very diverse, but all patients have serology, histology, and genetic tests compatible with CD.

2. Subclinical: Patients do not show symptoms or signs, although the rest of the diagnostic tests are positive.

3. Latent: These are patients who, at a certain time, while consuming gluten, do not present symptoms and the intestinal mucosa is completely normal.

4. Refractory. This is a very rare form consisting of a lack of response to the gluten-free diet and can be associated with intestinal complications [2].

3. Etiological theories

The cause/s of celiac intolerance are generally unknown, but they are probably related to the presence of one favorable genetic susceptibility to the development of gluten intolerance. Thus, various environmental agents have been implicated, such as an increased and continued consumption of foods rich in gluten, as well as probably the presence of triggering viral, bacterial, or parasitic infections.

There is a great overlapping between CD and other autoimmune diseases.

4. Symptomatology

The clinical symptoms are diverse, the most frequent being those of a digestive type such as abdominal distension, nausea, vomiting, diarrhea, abdominal pain, and meteorism, generally accompanied by a decrease in appetite, as well as muscle mass loss, weight, increased tiredness, growth retardation, character changes (irritability, apathy, introversion, sadness, etc.), iron deficiency anemia resistant to treatment, etc. However, in both children and adults, the symptoms may be atypical, or completely absent, making diagnosis difficult [3].

It is estimated that a very high percentage of patients (>75%) are undiagnosed, largely due to the ignorance of primary care physicians, who are the first filter through which celiac people pass. The lack of knowledge about the heterogeneity of the possible symptoms associated with celiac disease in the medical community can cause a significant delay of several years or even a lack of diagnosis. However, the recognition of other atypical and asymptomatic forms of manifestation, combined with the greater and better use of the complementary tests available, has made it possible to reveal the existence of different types of celiac disease.

5. Diagnostic procedures

Diagnosis of celiac disease can be difficult because the symptoms caused by this disease can also appear in many other diseases. Patients with celiac disease usually have elevated serum levels of antibodies against gluten (i.e., anti-gliadin antibodies, anti-transglutaminase, anti-endomysium, and also anti-gliadin deamidated peptide antibodies). If the levels of these antibodies in the blood are elevated then it helps to get a positive diagnosis. The best way to confirm the disease is to perform a duodenoscopy taking several biopsies of the intestinal mucosa to evaluate the degree of inflammatory lesions and the presence or absence of associated villous atrophy. Doubtful cases is useful to perform a flow cytometric study of the duodenal biopsies, in order to classify the lymphocytes subpopulations presented [4].

6. Duodenal biopsies

The confirmation of the diagnosis today is based on the concurrence of clinical suspicion, positive serology, presence of a compatible genetic susceptibility, and findings at the intestinal biopsies compatible with celiac disease.

7. Gluten-free diet

The only treatment for celiac disease is to avoid completely the consumption of foods containing gluten, even in minimal amounts.

Once the gluten-free diet (GFD) is established, the clinical recovery is usually not immediate, and duodenal biopsies can be repeated after 2 years to return to being completely normal [5].

At the beginning of the treatment, in addition to the GFD, dietary supplements of vitamins or minerals can be recommended in some people which show deficiencies and usually, they achieve a faster recovery.