What is celiac disease?
Celiac disease is a multisystem autoimmune disease caused by an abnormal immune response to gluten – a mixture of proteins found in wheat and other cereals – in genetically susceptible individuals. This inflammatory reaction damages the mucosa of the small intestine, causing a wide range of clinical manifestations from classic gastrointestinal symptoms to atypical signs or even no obvious symptoms at all. Although celiac disease has a clear genetic component of predisposition, it is not considered a hereditary disease in the strict sense, as it is the risk of developing the disease that is inherited and not the disease itself. Its onset does not depend solely on gluten intake, but on a combination of environmental factors (such as taking antibiotics at an early age or even acute viral infections and other situations of digestive stress that can alter the intestinal microbiota).
Prevalence and importance of early diagnosis in celiac condition
The overall prevalence of celiac disease in Western countries is estimated to be around 1-2% of the Western population, affecting all ages equally and with a 2:1 ratio of women to men, although many people remain undiagnosed due to the diversity of clinical manifestations of the disease. Early and accurate diagnosis is essential to prevent long-term complications such as malnutrition, osteoporosis, infertility, neurological disorders or even intestinal lymphoma.
Thanks to advances in diagnostic biotechnology and the standardisation of international clinical criteria, such as those proposed by ESPGHAN (European Society for Paediatric Gastroenterology, Hepatology and Nutrition), it is now possible to establish a more efficient and less invasive diagnosis, especially in the paediatric population.
How is celiac disease diagnosed?
The diagnosis of celiac disease must be based on a combination of clinical, serological, genetic and histological factors. No single test is sufficient to confirm or rule out the disease completely, although a combination of methods has been shown to be highly accurate:
- Clinical suspicion: first-degree relatives of people with celiac disease, autoimmune diseases such as type I diabetes, neurological and psychiatric disorders, other genetic associations such as Down syndrome or Williams syndrome, compatible symptomatology….
- Serological markers: Anti-tissue transglutaminase antibodies (IgA anti-tTG) are the most widely used markers of coeliac disease due to their excellent sensitivity and specificity in the active phase. They are the first step in the screening of patients with clinical suspicion. Other complementary markers include:
- Anti-endomysial antibodies (IgA anti-EmA), very specific for celiac disease and useful as a confirmatory test.
- Anti-deamidated gliadin peptide antibodies (anti-DGP), more sensitive in young children (<2 years) than tTG and EmA. They are also useful in patients with IgA deficiency.
- Genetic testing: Genetic predisposition is a prerequisite for the development of celiac disease. Almost all patients carry HLA-DQ2.5 and/or HLA-DQ8 haplotypes. Their absence allows the disease to be ruled out with a high negative predictive value, which is useful in doubtful cases or in families with celiac disease.
- Intestinal biopsy: Biopsy remains the standard in adults and in children who do not meet the criteria for diagnosis without biopsy. It assesses the degree of atrophy of the intestinal villi using the Marsh-Oberhuber classification. It is an invasive test, but essential in some cases to confirm the diagnosis.
Diagnostic protocol according to ESPGHAN
The latest update of the ESPGHAN guidelines (2020) has brought about a paradigm shift in paediatric diagnosis. Under certain strictly defined conditions, it is possible to establish a diagnosis of celiac disease without the need for an intestinal biopsy, reducing invasiveness, costs and time to initiation of treatment.
Criteria for avoiding biopsy in paediatric patients
In patients with compatible symptoms, the diagnosis can be established without biopsy if the following criteria are met simultaneously:
- IgA anti-tTG antibodies ≥ 10 times the upper limit of normal, using accurate and proven tests.
- Confirmation of positive IgA anti-EmA antibodies in a second sample.
This protocol significantly reduces the need for endoscopy in the paediatric population without compromising diagnostic confidence. However, in cases where anti-tTG is < 10 times the upper limit of normal and anti-EmA is positive, as well as in asymptomatic type 1 diabetic patients, biopsy should be performed.
The complete guide can be found here.
Diagnostic tools available
OPERON, as IVD test manufacturers, offers to health professionals and distributors a complete line of tools for the diagnosis of celiac disease, both at serological and genetic level. Our products are CE-IVD marked, comply with European quality standards and are designed to facilitate accurate clinical decision making in the shortest possible time.
Rapid tests for antibody detection
They provide in-office qualitative screening, ideal for settings without immediate laboratory access or as a first step in a tiered approach, thus reducing healthcare costs and avoiding more invasive tests such as serology due to their negative predictive value.
Simple CD2WB
- Sample type: blood, serum or plasma
- Detection: IgA anti-tTG and anti-DPG antibodies in differential bands
- Results: 10 minutes
- Application: rapid diagnostic guidance in consultation, paediatrics, gastroenterology, especially in patients < 2 years old
Simple CD1WB
- Type of sample: blood, serum or plasma
- Detection: Igs anti-tTG antibodies
- Results: 10 minutes
- Application: rapid diagnostic guidance in consultation, paediatrics, gastroenterology, especially in patients with IgA deficiency
In the case of CD2WB, the combination of two markers improves diagnostic sensitivity, especially in children under 2 years of age with low anti-tTG IgA levels. Furthermore, its complementary use with CD1WB facilitates the evaluation of patients with IgA deficiency.
Genetic testing for celiac disease
This test provides key information on the genetic predisposition to celiac disease and allows the pathology to be ruled out if haplotypes are negative, thus avoiding unnecessary screening.
CeliacStrip
- Sample type: DNA
- Detection: HLA-DQ2.5, HLA-DQ8, HLA-DQ2.2 and HLA-DQ7.5 cellular receptors by detection of HLA-DQA1, HLA-DQB1 and HLA-DRB1 alleles
- Application: patients with doubtful serology, relatives of celiac patients and/or risk groups, genetic screening
All products are designed to optimise diagnostic time and improve care efficiency, adapting to clinical laboratories as well as specialised and point of care practices.
Conclusions
Accurate and early diagnosis of celiac disease is essential to avoid long-term complications. Although the diagnostic protocol is mainly based on laboratory serology, genetics and intestinal biopsy, the use of complementary tools such as rapid tests are of increasing value in the diagnostic process, especially in the consultation.
Rapid tests such as Simple CD2WB and Simple CD1WB allow qualitative detection of the relevant antibodies (anti-tTG and anti-DGP) in the office with only a drop of blood. These tests are useful as an initial screening tool in patients with clinical suspicion, especially in young children or in resource-limited settings. Although they do not replace quantitative laboratory serology, their high negative predictive value may reduce the need for invasive testing in certain clinical profiles.
On the other hand, the CeliacStrip genetic test can determine whether a patient has the genetic predisposition to develop the disease, making it a key tool to rule out celiac disease in cases with ambiguous serology results, first-degree relatives or at-risk groups, thus avoiding unnecessary screening and optimising patient management.
