Celiac disease (CD) is the most common genetically related food intolerance, worldwide. Celiac disease is a multifactorial, autoimmune disorder that occurs in genetically susceptible individuals.[1] It is triggered by a well-identified environmental factor (gluten and related prolamins present in wheat, rye, and barley), and the autoantigen is also well known (ie, the ubiquitous enzyme tissue transglutaminase). The disease primarily affects the small intestine, where it progressively leads to flattening of the small intestinal mucosa.
Within this definition, patients can further be defined as having silent, potential, or latent celiac disease.[2] The term silent celiac disease refers to patients fulfilling the definition above, but presenting no symptoms. Typically, such diagnoses are made by screening asymptomatic individuals who are at increased risk for celiac disease. The term potential celiac disease describes patients who have specific serum autoantibodies and may or may not have symptoms consistent with celiac disease, but lack evidence of the autoimmune insult to the intestinal mucosa. A final category of celiac patients is represented by the so-called latent celiac disease: individuals with normal mucosal morphology (like the potential) but known to have had a gluten-dependent enteropathy at some point in their life.
The genetic susceptibility to celiac disease is conferred by well-identified haplotypes in the human leukocyte antigen (HLA) class II region (ie, DR3 or DR5/DR7 or HLA DR4). Such haplotypes are expressed on the antigen-presenting cells of the mucosa (mostly dendritic cells); approximately 90% of patients express the DQ2 heterodimer, and approximately 7% of patients express the DQ8 heterodimer. The remaining 3% of patients possess only half of the DQ2 heterodimer.
Celiac disease can occur at any stage in life; a diagnosis is not unusual in people older than 60 years.
Data from Rubio-Tapia et al[3] showed that undiagnosed celiac disease in the United States has dramatically increased in the past half century, going from 0.2% in the late 1940s to 0.9% 50 years later.
Celiac disease is an autoimmune disease, and the enzyme tissue transglutaminase (tTG) has been discovered to be the autoantigen against which the abnormal immune response is directed. Gluten is the single major environmental factor that triggers celiac disease, which has a narrow and highly specific association with class II haplotypes of HLA DQ2 (haplotypes DR-17 or DR5/7) and, to a lesser extent, DQ8 (haplotype DR-4).
Scientific knowledge on the pathogenesis of celiac disease has markedly increased in the past few years; the combined roles of innate and adaptive immunity are now better understood.
Intraepithelial lymphocytes (IELs) play an important role in the destruction of epithelial cells. Through specific natural killer receptors (NKR) expressed on their surface, IELs recognize nonclassical major histocompatibility complex (MHC)-I molecules induced on the surface of enterocytes by stress and inflammation. This interaction leads to activation of these armed effector IELs to become lymphokine-activated killing cells; they cause epithelial cell death in a T-cell receptor (TCR)–independent manner. This killing is particularly enhanced through the cytokine interleukin (IL)-15, which is highly expressed in celiac mucosa. NKG2D has been found to play a crucial role in intestinal inflammation in celiac disease.[4]
The adaptive immune response to gluten has been well described, with the identification of specific peptide sequences demonstrated in specific binding to HLA-DQ2 or DQ8 molecules and in stimulating gluten-specific CD4 T cells. These T cells express α/β TCR, and can be isolated from the lamina propria and cultivated. In vitro, they have been shown to recognize specific gluten peptides presented through interaction with DQ2 or DQ8 molecules.
Gluten is a complex macromolecule that contains abundant proline and glutamine residues, rendering it largely indigestible. Under usual circumstances, gluten is left (in part) unabsorbed by the GI tract. Gluten is composed of glutenins and gliadins, the alcohol-water soluble fraction. These gliadins are further divided into alpha, gamma, and omega fractions based on electrodensity.[5]
Among these fractions, one particular peptide fragment is the alpha gliadin 33-mer, which contains an immunodominant peptide fragment. This fragment is deamidated by tTG. tTG is a ubiquitous enzyme and is known to deamidate glutamine to glutamic acid, creating a strong negative charge within the peptide. This modification is crucial in increasing selection to the positive charges within the binding pocket of HLA-DQ2 or DQ8 molecules on antigen-presenting cells in the lamina propria. When conveyed to gluten specific CD4+ T cell, it induces proliferation and induction of a Th1 cytokine response, primarily with the release of interferon-γ.
B cells receive signals through this HLA interaction, leading to tTG autoantibody production. The role of these autoantibodies is still unclear; they have been shown to be deposited along the subepithelial region even in normal-appearing intestinal biopsy findings prior to positive serology and without the onset of overt epithelial cell damage.
Celiac disease primarily affects the small intestine. This organ is schematically divided into three areas: the duodenum (which begins beyond the pylorus, located at the end of the stomach), the jejunum, and the ileum (ending at the ileocecal junction, the beginning of the large intestine). These three parts share similar tissue architecture and are responsible for most of the body's nutrient absorption. The intestinal wall has four layers, which (from the lumen inward) are termed the mucosa, submucosa, muscularis, and serosa. The two main functions of the mucosa are to accomplish all digestive-absorptive processes for nutrients and electrolytes and to provide a barrier function by excluding foreign antigens and toxins.
Celiac disease affects the mucosal layer: here, a cascade of immune events leads to the changes that can be documented by histology.
The classic celiac lesion occurs in the proximal small intestine with typical histological changes of villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytosis. Three distinctive and progressive histological stages have been described and are termed the Marsh classification.[6] The histological changes of celiac disease are classified as follows:
United States
The availability of sensitive and specific serological tests has made it possible to assess the true prevalence of celiac disease by detecting minimally symptomatic or even asymptomatic cases with typical mucosal changes.[7] Screening studies have shown that celiac disease has a very high prevalence, occurring in almost 1% of the general population throughout North America.[8, 9]
International
Celiac disease is as common in Europe as it is in North America, but it has now been detected in populations from many other parts of the world, including African and Middle Eastern countries, and in Asia, with the highest prevalence worldwide in Saharawi children.[10]
Furthermore, the prevalence of celiac disease appears to be increasing quite dramatically during the past few decades.[8, 11, 12, 9] In Northern Sweden, an epidemiological investigation using a combined serological/endoscopic approach in an unselected population of 1000 adults found a prevalence of almost 2%.[13]
Epidemiological data do document worldwide a true increase in prevalence, with rates doubling approximately every 20 years. A concomitance of environmental factors are likely responsible for this, but most of them are still unclear. Among the hypotheses to explain such increase are: the hygiene hypothesis,[14] increased rates of births through elective cesarean delivery,[15] changes in infant feeding practices as dramatically documented by the so-called Swedish epidemic,[16] and repeated infections—by rotavirus but also generic, nongastrointestinal infections in early infancy.[17]
A recent investigation in Sweden proved that early vaccinations are not risk factors for the development of celiac disease.[18]
A study reported that children living in socioeconomically deprived areas in the UK are less likely to be diagnosed with CD. The study added that increased implementation of diagnostic guidelines could result in better case identification in more-deprived areas.[19, 20]
The morbidity rate of celiac disease can be high. Its complications range from osteopenia, osteoporosis, or both to infertility in women, short stature, delayed puberty, anemia, and even malignancies (mostly related to the GI tract [eg, intestinal T-cell lymphoma]). As a result, the overall mortality in patients with untreated celiac disease is increased.
Evidence also suggests that the risk of mortality is increased in proportion to the diagnostic delay and clearly depends on the diet; subjects who do not follow a gluten-free diet have an increased risk of mortality, as high as 6 times that of the general population. The increased death rates are most commonly due to intestinal malignancies that occur within 3 years of diagnosis.[21, 22] Some indirect epidemiological evidence suggests that intestinal malignancies can be a cause of death in patients with undiagnosed celiac disease.[23]
In some ethnicities, such as in the Saharawi population, celiac disease has been found in as many as 5% of the population. As mentioned, celiac disease is considered extremely rare or nonexistent in people of African, Chinese, or Japanese descent.
Most studies indicate a prevalence for the female sex, ranging from 1.5:1 to 3:1.
Celiac disease can occur at any stage in life; a diagnosis is not unusual in people older than 60 years. Classic GI pediatric cases usually appear in children aged 9-18 months. Celiac disease may also occur in adults and is usually precipitated by an infectious diarrheal episode or other intestinal disease.
The prognosis for celiac disease is excellent; the disorder is fully reversible if trigger foods are avoided.
A consensus report by Ludvigsson et al stated that in adolescence, patients with CD should gradually assume exclusive responsibility for their own care, learning how to follow a gluten-free diet and the consequences of not following it.[24]
In modern society, living a life without gluten is not easy. Educating patients and their families about how to select and properly maintain such a diet is a major, ongoing task.
The role of support groups can never be overestimated. The physician has a duty to care for patients with celiac disease and to adequately inform the family about how to connect with such groups.
Several university-associated centers that provide excellent materials for patient education are now available in the United States (eg, the University of Chicago Celiac Disease Center) and in Europe. In the United States, the American Celiac Disease Alliance (ACDA) offers patient education as well as links to other centers.
For excellent patient education resources, see the Digestive Disorders Center and Skin Conditions & Beauty Center. Also, see the patient education articles Celiac Disease, Anatomy of the Digestive System, and Canker Sores.
Celiac disease (CD) may occur without any symptoms; asymptomatic or minimally symptomatic celiac disease is probably the most common form of the disease, especially in older children and adults. See the figures below.
View Image | The celiac iceberg. |
View Image | Presentations of celiac disease. |
Currently,[2] 5 possible presentations of celiac disease are recognized, as follows:
The so-called typical form of celiac disease presents with GI symptoms that characteristically appear at age 9-24 months. Symptoms begin at various times after the introduction of foods that contain gluten. Infants and young children typically present with chronic diarrhea, anorexia, abdominal distension, abdominal pain, poor weight gain or weight loss, and vomiting. Severe malnutrition can occur if the diagnosis is delayed. Behavioral changes are common and include irritability and an introverted attitude. Rarely, severely affected infants present with a celiac crisis, which is characterized by explosive watery diarrhea, marked abdominal distension, dehydration, hypotension, and lethargy, often with profound electrolyte abnormalities, including severe hypokalemia.
Older children with celiac disease who present with GI manifestations may have onset of symptoms at any age. The variability in the age of symptom onset possibly depends on the amount of gluten in the diet and other environmental factors, such as duration of breast feeding. In fact, in the author's experience, if gluten is introduced during breast feeding, the symptoms tend to be less often GI related and tend to appear later in life.[25] GI symptoms in older children are typically less evident and include nausea, recurrent abdominal pain, bloating, constipation, and intermittent diarrhea.
A study by Mårild et al reported a two-way association between anorexia nervosa and celiac disease. The hazard ratio for future anorexia nervosa after celiac disease diagnosis was 1.46 and 1.31 beyond the first year. The odds ratio for a previous anorexia nervosa diagnosis associated with celiac disease was 2.18.[26, 27]
An increasing number of patients are being diagnosed without typical GI manifestations at older ages. A reasonable assumption is that approximately 70% of patients with newly diagnosed celiac disease do not present with the typical major GI symptoms. Once again, a relationship between the age of onset and the type of presentation is noted; in infants and toddlers, GI symptoms and failure to thrive predominate, whereas, during childhood, minor GI symptoms, inadequate rate of weight and height gain, and delayed puberty tend to be more common. In teenagers and young adults, anemia is the most common form of presentation. In adults and in the elderly, GI symptoms are more prevalent, although they are often minor. See the images below.
View Image | GI signs and symptoms of celiac disease. |
View Image | Extraintestinal manifestations of celiac disease. |
The main extraintestinal manifestations of celiac disease are as follows:
Celiac disease is also known to be strongly associated with numerous disorders, specifically with autoimmune conditions and genetic syndromes (eg, Down syndrome, Williams syndrome, Turner syndrome).
The association of celiac disease with autoimmune conditions is well known. A strong positive correlation between the age at diagnosis and the prevalence of autoimmune disorders (eg, type 1 diabetes mellitus, thyroiditis, alopecia) is recognized; this suggests that the continuous ingestion of gluten before diagnosis may induce the development of other autoimmune conditions.
Type 1 diabetes mellitus
Approximately 10% of patients with type 1 diabetes mellitus have typical findings of celiac disease on duodenal biopsy samples.
Many individuals with type 1 diabetes mellitus who initially had negative serological test results for celiac disease eventually had positive findings; this highlights the need for repeated testing.
Because celiac disease only occurs with specific human leukocyte antigen (HLA) haplotypes, an algorithm based on the determination of these HLA haplotypes has been proposed to avoid repeat testing in all patients with diabetes; this allows patients with diabetes in whom the HLA haplotypes are inconsistent with celiac disease to avoid repeat testing.
Typically, diagnosis of diabetes precedes diagnosis celiac disease by years; celiac disease in these patients most commonly presents with mild GI symptoms or absent symptoms. Because some of these symptoms are also seen in patients with diabetes (eg, bloating, diarrhea), diagnosis of celiac disease may be missed unless a screening is performed.
Although no convincing evidence has suggested that a gluten-free diet has any obvious effect on diabetes, these patients must follow the diet to prevent all long-term complications of celiac disease. Thus, screening patients with type 1 diabetes mellitus for celiac disease seems well founded.
Of interest, while the increased prevalence of celiac disease in patients with type 1 diabetes is well recognized, the reverse is not true: there seems to be no increased prevalence of type 1 diabetes in patients who had been diagnosed with celiac disease.
Down syndrome
The best documented and most well-known nonautoimmune disorder associated with celiac disease is Down syndrome.
As assessed by screening methods, the prevalence of Down syndrome in celiac disease is 8-12%.
Most patients with Down syndrome who have celiac disease have some GI symptoms, such as abdominal bloating, intermittent diarrhea, anorexia, or failure to thrive; however, about one third of these patients do not have GI symptoms.
As with patients who have type 1 diabetes mellitus, periodic serologic testing is indicated only in patients with Down syndrome who are genetically compatible with celiac disease (ie, those who have either HLA DQ2 or DQ8).
A similar strategy should be applied for patients with Turner syndrome or Williams syndrome, in whom an increased incidence of celiac disease has also been reported.
A study by Mårild et al found that in a review of pathology records of 7548 females with CD in Sweden, that 20 of the patients (0.26%) also had a diagnosis of Turner syndrome. In contrast, among 34,492 age- and sex-matched controls in the general Swedish population, only 21 (0.06%) had a Turner syndrome diagnosis which corresponded to an odds ratio for celiac disease of 3.29 (95% confidence interval [CI], 1.94 - 5.56).[33, 34]
Examination findings depend on extent of celiac disease.
Birth modalities appear to influence the onset of celiac disease in genetically predisposed individuals, likely due to the abnormal microbiota in babies born via a cesarean delivery.[35]
Breastfeeding has a protective role.[36] Having gluten introduced while breast feeding is continued has a strong protective effect.[37] Additionally, early (age ≤3 mo) first exposure to gluten may favor the onset of celiac disease in predisposed individuals. Large amounts of gluten at weaning are associated with an increased risk for developing celiac disease, as is documented in studies from Scandinavian countries.[38] Finally, repeated rotavirus infections,[39] but also other infections,[17] in infancy appear to be associated with a higher risk of developing celiac disease autoimmunity in genetically predisposed individuals.
No role for vaccinations in favoring celiac disease has been demonstrated.[18]
Celiac disease is fully reversible—in the majority of patients—if trigger foods are avoided. However, when compliance is suboptimal, complications may occur. The level of gluten that is safe to consume widely varies among people with celiac disease; hence, a zero-tolerance policy must be enforced. Available evidence suggests that although almost no individuals with celiac disease show signs or symptoms of relapse while ingesting as much as 10-20 mg of gliadin per day, most react to ingestion of more than 100 mg/d.[40]
A population-based study by Canova et al found no evidence of an increased risk of fractures for pediatric celiac disease patients (overall hazard ratio 0.87).[41]
Duodenal mucosa histology changes in celiac disease (CD) are documented while on a gluten-containing diet and are characterized by a progressive deterioration of the villous architecture associated with a progressive increase in crypt length and density. Biopsy samples are now almost universally obtained by endoscopy. Multiple biopsy samples (at least four) are recommended because celiac disease may be patchy and areas of villous atrophy may be adjacent to normal areas.[42] In addition, biopsy from the duodenal bulb is also recommended, as about 2-3% of celiac children may have changes only in that part of the duodenum.[43] Although endoscopically visible changes have been described (eg, scalloping or nodularity of the mucosa, sparse duodenal folds), such changes are neither constant nor specific, and a diagnosis of celiac disease should never be based on their presence or absence.
In 2012, new diagnostic guidelines were introduced by the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition (ESPGHAN).[2] While confirming the same diagnostic process previously recommended by both the North American Society for Pediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) in 2005[44] and those published by the American Gastroenterological Association (AGA) in 2006,[45] the new guidelines allow avoiding the confirmatory duodenal biopsy in selected cases, characterized by a child or teenager with gastrointestinal signs or symptoms consistent with celiac disease, a compatible HLA status, levels of tissue transglutaminase (TTG) elevated more than 10-fold, and positive endomysium (EMA).
In clinical practice, it is thus recommended to obtain first serologic tests for celiac disease (namely the anti-TTG-IgA) and then to proceed with the intestinal biopsy to diagnose the condition in positive cases. Serology, especially TTG, also has a major role in monitoring response to treatment.
The TTG and the EMA-IgA tests are both highly sensitive and highly specific, with values for both parameters exceeding 96% in most studies. No identifiable differences between adults and children are noted with respect to these tests, with the exception of very young children, younger than 2 years, for whom especially the sensitivity may be less than optimal. In this young age group, the use of deamidated gliadin peptides (DGPs) has been proposed, as they appear to have a better sensitivity.[46] DGPs are otherwise consistently overlapping with TTG in other age groups as for sensitivity and specificity.[47]
Radiography of the GI tract with a barium swallow study and a small intestinal follow-through may show nonspecific changes because of the mucosal inflammation and possible concomitant protein-losing enteropathy (edema of the bowel walls, dispersion of the barium column). The findings are clearly nonspecific, and radiographic investigation is not indicated.
Most centers today include diagnostic duodenal biopsy during esophagogastroduodenoscopy (EGD). Obtaining at least four biopsy samples from the distal duodenum and one or two from the bulb is highly recommended because mucosal changes in celiac disease may be patchy. Colonoscopy may be indicated only if bloody stools are reported or if symptoms of colitis are also present.
Mucosal biopsy of the duodenum shows the changes described in Workup. However, changes referred to as Marsh 1 or even Marsh 2 are nonspecific because they can also be found in food-allergic enteropathies, such as cow's milk allergy or soy allergy (especially in infancy). These changes are also observed in giardiasis and in autoimmune enteropathy.
Although also not pathognomonic for celiac disease, changes referred to as Marsh 3 are usually much more specific, especially if they are associated with supportive serology findings.
Evidence suggests that patients with Marsh type 1 changes who have a positive serology findings may develop more severe changes if they continue a gluten-containing diet; this challenges the idea that celiac disease is only observed in those who have more advanced findings.[48]
Total lifelong avoidance of gluten ingestion is the cornerstone treatment for patients with celiac disease (CD). Wheat, rye, and barley are the grains that contain toxic peptides. They should be eliminated as completely as possible, although daily intake doses larger than 10 mg are likely needed to cause mucosal reaction.[40] GI symptoms in patients with symptomatic celiac disease who adhere to a gluten-free diet typically resolve within a few weeks; these patients experience the normalization of nutritional measures, improved growth in height and weight (with resultant normal stature), and normalization of hematological and biochemical parameters.
Furthermore, treatment with a gluten-free diet reverses the decrease in bone mineralization and the risk for fractures . Symptomatic children treated with a gluten-free also improve their sense of physical and psychological well being.
Of note, in recent years, the possibility of incomplete remission in many adult celiac patients has been emerging.[49] This seems, however, in most cases, still related to ongoing ingestion of minimal amounts of gluten, possibly through cross-contamination.
The results from one study noted no significant difference in thyroid autoimmunity presence in patients with CD between those on a gluten-free diet and those who were not. While the duration of the diet differed significantly in patients with thyroid autoimmunity than those without, it did not seem to affect weight and height gain. These results suggest that universal long-term screening programs for thyroid disease may only be necessary when thyroid diseases are suspected.[50]
For a long time, oats were considered toxic as well, and their elimination from the diet had been recommended. However, over the past decade, a growing body of scientific evidence obtained from in vitro studies as well as from clinical investigations (particularly in adults but also, more recently, in children) suggests that oats are totally safe. Because of uncontrolled harvesting and milling procedures, as well as the possibility that lines of manufacturing used for wheat-based flours are also used in the preparation of oat-based foods, cross-contamination of oats with gluten is still a concern.
Lactose is often eliminated in the initial phases of dietary treatment as well. This is because lactase deficiency is thought to accompany the flat mucosa. However, most newly diagnosed patients with celiac disease are diagnosed in the absence of overt malabsorptive symptoms; in these circumstances, clinically significant lactose malabsorption or intolerance is rarely seen. Furthermore, even in cases with obvious malabsorption, the recovery of lactase activity is typically fast; thus, a lactose-free diet must be used on a short-term basis only, even in these individuals.
The Academy of Nutrition and Deietetics (AND) (once American Dietetic Association (ADA)) publishes guidelines for the dietary treatment of celiac disease. They are a reliable source of information for a gluten-free. However, because of the dynamics of this field, the diet requires ongoing collaboration between patients, health care providers, and dietitians.
Because of the protean nature of celiac disease, multiple consultations may be necessary. For example, consultations with an endocrine specialist should be arranged for patients who also have Hashimoto thyroiditis or type I diabetes mellitus, and a rheumatologist must be consulted for patients who have arthritis.
No additional restriction is necessary beyond that imposed by the patient's fatigue. However, if a completely gluten-free diet is followed, celiac disease completely regresses, and individuals have a completely normal quality of life.
The only way to prevent recurrences is to closely monitor the patient's diet. Because celiac disease is more common in relatives of patients, first-degree relatives should at least be serologically screened (see Causes). Concerned parents usually accept this simple procedure, which often reveals previously undetected celiac disease, even in asymptomatic individuals. This effective preventive strategy must be encouraged.
Also, prevention of complications by early diagnosis (secondary prevention) may be achieved by applying a protocol of blood screening to all patients who belong to other at-risk categories (eg, type 1 diabetes mellitus, Down syndrome).
With elucidation of the role that infant feeding practices and rotavirus infections play, primary prevention of celiac disease no longer seems impossible. Primary prevention (at least in some cases) may be achieved through the expected reduction of rotavirus infections after the introduction of the vaccine and through proper breast feeding and gluten introduction in infants born to at-risk families.
After the diagnosis of celiac disease (CD) has been established and a strict diet has been initiated, the first follow-up requirement is to monitor the patient's response to the diet. Depending on the severity of the clinical situation and the type of symptoms, the first outpatient appointment is typically scheduled for 4-8 weeks after the diagnosis. At this time, serologic tests for celiac disease are not needed because antibody levels still have not declined.
Further follow-up appointments are dedicated to assessing the patient's dietetic compliance and the adequacy of growth and well-being. Anti-tTG and the newer deamidated antigliadin antibodies should be periodically monitored for regression; their levels usually return to normal within 4-6 months after the beginning of a rigorous diet. However, the best indicator of dietary compliance is attainable by a careful review of the diet, and simple survey questionnaires have been developed for use in adults.[51] For patients whose initial levels of anti-tTG were particularly elevated, normalization can take up to 12-18 months. For asymptomatic patients and for those who are clinically responding well to diet, follow-up appointments are usually scheduled annually.
Celiac disease can be associated with numerous autoimmune disorders. If any are present (eg, type I diabetes mellitus, thyroiditis), follow-up care must include an adequate assessment of these conditions, which most often do not respond to the diet, and referral to other specialists is required (see Consultations).
A dietitian must be present at each of the follow-up appointments because the questions that most interest the patient's family are, by far, those concerning the diet.
In patients who had obvious malabsorption at diagnosis, assessment of the status of specific nutritional deficiencies (eg, iron deficiency, folate deficiency, zinc deficiency) is appropriate.
The European Society for the Study of Coeliac Disease (ESsCD) and the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) have published guidelines for the diagnosis and management of celiac disease (sprue). These guidelines are summarized below.
In October 2019, the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) published guidelines for the diagnosis of celiac disease (sprue).[54]
There is no need for HLA-DQ2 and HLA-DQ8 typing in patients with positive transglutaminase immunoglobulin A (TGA-IgA) if they qualify for celiac disease (CD) diagnosis with biopsies or if high serum TGA-IgA (≥10 times the upper limit of normal [ULN]) and endomysial antibody (EMA)-IgA positivity exist. While patients testing negative for HLA-DQ2 and HLA-DQ8 have a very low CD risk, the diagnosis is not confirmed with a positive result.
If serum IgA values are normal for age, TGA-IgA should serve, regardless of patient age, as the initial serologic test.
Children with suspected CD should undergo total IgA and TGA-IgA testing as an initial screen. If total IgA concentrations are low, the second step should consist of an IgG-based test (deamidated gliadin peptide [DGP], EMA, or TGA). Testing for EMA, DGP, or AGA antibodies (IgG and IgA) is not recommended as an initial screen in clinical practice.
The TGA-IgA serum concentration should be at least 10x ULN for a diagnosis of CD made without biopsies. Antibody tests should be used only if they have proper calibration curve–based calculation and their measurement range accommodates a 10x ULN value. In patients in whom IgA is deficient but IgG-based serologic tests are positive, biopsies should not be omitted.
If the parents/patient have agreed to a no-biopsy approach to CD diagnosis, a positive EMA-IgA test performed on a second blood sample should be used to confirm the diagnosis in children with TGA ≥10x ULN.
While the patient is on a gluten-containing diet, histologic evaluation should be carried out using at least four biopsies from the distal duodenum and at least one from the duodenal bulb. Optimally orientated biopsies should be assessed. The presence of mucosal lesions is indicated by a villous-to-crypt ratio of less than 2. If the TGA results are discordant with the histopathology, the biopsies should be recut and/or a second opinion should be obtained from an experienced pathologist.
It is not necessary to consider that other pathologies or diagnoses may have been missed if the CD diagnosis omits upper endoscopy with biopsies.
In June 2019, the European Society for the Study of Coeliac Disease (ESsCD) released updated guidelines for the management of celiac disease (CD) and other gluten-related disorders in adults and children.[52, 53] Their strong CD recommendations are outlined below.
Adult patients with symptoms, signs, or laboratory evidence suggestive of malabsorption: Test with serology for CD.
Patients with unexplained elevation of serum aminotransferase levels: Exclude CD.
Patients with type 1 diabetes: Screen regularly for CD.
Serology
IgA-TG2 (immunoglobulin A-tissue transglutaminase 2) antibody is the preferred single test for CD detection at any age. Concurrently measure total IgA level with serology testing to determine whether IgA levels are sufficient.
At diagnosis and follow-up, perform IgG-based testing (IgG-DGPs [deamidated gliadin peptides] or IgG-TG2) in patients with selective total IgA-deficiency.
Perform all diagnostic serologic testing while patients are on a gluten-containing diet.
Antibodies directed against native gliadin (AGA) are not recommended for primary CD detection.
Endoscopy and histopathology
When CD is suspected, obtain biopsies even with a normal endoscopic appearance of the duodenum.
Duodenal biopsy is an essential component of the diagnostic evaluation for adults with suspected CD and is recommended to confirm the diagnosis. Multiple duodenal biopsies (at least four of the second part of duodenum) are recommended for confirmation.
An increase in intraepithelial lymphocyte (IEL) infiltration in the absence of villus atrophy (VA) in duodenal biopsies (Marsh 1) is not specific for CD; exclude other causes.
Helicobacter pylori infection is often associated with Marsh 1 histology; its eradication may normalize the duodenal IEL count. Obtain concomitant gastric biopsies or perform serology when H pylori is suspected.
If CD is highly suspected, perform duodenal biopsy even if the serology is negative.
HLA-DQ2/8 typing
Avoid routine use of HLA-DQ2/DQ8 testing in the initial diagnosis of CD. Include the results of such testing with a caution that patients at risk should be serologically tested for CD without changing their diet.
Use HLA-DQ2/DQ8 testing to rule out CD in selected clinical situations, including: (a) Marsh 1-2 histology in seronegative patients; (b) evaluation of patients not tested for CD before initiation on a gluten-free diet (GFD); (c) discrepant results of celiac-specific serology and histology.
Other diagnostic tests
Video capsule endoscopy (VCE) is not used for the initial diagnosis of CD except for patients with positive celiac-specific serology who are unwilling/unable to undergo endoscopy with biopsy. VCE is important in detecting complications associated with CD.
Intestinal-permeability tests are neither sensitive nor specific and are not recommended for CD diagnosis.
Serum intestinal fatty acid binding protein (I-FABP) might be useful in identifying dietary nonadherence and unintentional gluten intake.
Diagnostic confirmation
Diagnostic confirmation of CD in adults and in some children should be based on clinical data, positive serology, and duodenal histology.
Improvement of symptoms or exacerbation after gluten re-introduction has a very low predictive value for CD and should not be used for diagnosis in the absence of other supportive evidence.
A positive CD-specific serology in patients with VA confirms the CD diagnosis.
In case of an elevated TG2-titer and normal histology, a pathologist familiar with CD should review the biopsies. Repeat the biopsy after gluten challenge if the patient was not on gluten-containing diet before testing. HLA-DQ2/8 typing is mandatory. Testing for other antibodies (eg, DGP and/or endomysium [EMA]) may be of added value.
Seronegative CD requires careful assessment with HLA-DQ2/8 testing and a response to a GFD after excluding other causes of seronegative VA. Coeliac serology, both IgA- and IgG-based, should be negative.
In patients who are already following GFD prior to testing, serology and HLA typing are needed. If serology is positive, then biopsy is the next step. Perform a gluten challenge when serology is negative but HLA DQ2/DQ8 is positive.
Patients with CD should adhere to a lifelong GFD. The majority of CD patients safely tolerate oats; introduction of oats into the diet should be cautious, and monitor patients for possible adverse reaction.
Refer patients with CD to a dietitian who is well-trained concerning CD to get a detailed nutritional assessment, education on the GFD, and subsequent monitoring.
Newly diagnosed adult CD patients should undergo testing to uncover deficiencies of essential micronutrients (eg, iron, folic acid, vitamins D and B12).
Advise patients to eat a high-fiber diet supplemented with whole-grain rice, maize, potatoes, and ample vegetables.
Monitor CD patients regularly for persistent or new symptoms, adherence to GFD, and assessment for complications. Base monitoring of GFD adherence on a combination of history and serology. Monitoring of CD patients should include verification of the normalization of laboratory abnormalities detected during the initial investigation.
Dietary revision should be performed by a dietitian with special expertise in CD especially in slow-responders to exclude gluten contamination.
A normal anti-TG2 level at follow-up does not predict recovery of VA.
A follow-up duodenal biopsy is recommended for monitoring in cases of lack of clinical response or relapse of symptoms despite a GFD.
CD patients who are known to be hyposplenic should receive the pneumococcal vaccine.
Measure bone density in those at high risk of osteoporosis at diagnosis, especially in those with malabsorption or those at high risk if there is a long delay in diagnosis, or there are clinical presentations suggestive of bone disease. In others, not later than age 30-35 years and then to be repeated at 5-year intervals. Use a shorter interval (2-3 years) in case of low bone density on index measurement, evidence of ongoing VA, or poor dietary adherence.
Carefully evaluate patients showing slow response to exclude dietary inconsistencies and also identify other specific etiologies. The evaluation should include review of the initial diagnosis, celiac serology, a dietary review, and a follow-up duodenal biopsy.
Distinguish RCD-I from RCD-II to select appropriate management and determine the prognosis. T-cell flow cytometry is the most reliable method to make a distinction between RCD-I and RCD-II.
Closely monitor the nutritional status of RCD patients. Nutritional support including parenteral nutrition forms an essential part of the management.
Confidently exclude enteropathy-associated T cell lymphoma (EATL) before initiating pharmacotherapy in RCD-II. RCD-II patients need to be treated in referral centers by an experienced gastroenterologist in CD with a hematologist.
Exclude EATL in any CD patient with abdominal pain, fever, obstruction, anemia, gastrointestinal bleeding, or unexplained weight loss.
In EATL, debulking surgery for large ulcerated small bowel tumors is recommended for limiting the risk of perforation or bleeding during chemotherapy.
Duodenal histology in some children is recommended to confirm the diagnosis of CD.
Introduce a GFD only when the CD diagnosis has been made conclusively.
A gradual, structured transfer of medical care of an adolescent with CD to adult care is recommended. Include as the minimum written information on the base of diagnosis, follow-up, anthropometric data, comorbidities, and dietary adherence.
For more information, please go to Celiac Disease (Sprue) and Genetics of Celiac Disease (Sprue).
For more Clinical Practice Guidelines, please go to Guidelines.
Clinical Context: Some cases of refractory celiac disease (with all other forms of colitis and enteritis excluded) respond to parenteral corticosteroids, for reasons unknown. Exclude other etiologies of failure to thrive, especially in children, because systemic steroids can pose risk to growth. Sodium succinate salt formulation may be administered IV or IM.
Corticosteroids can rapidly control severe symptoms of celiac disease (CD). They may also have a role in rare cases in which the patient has no response to diet; this condition is known as refractory celiac disease and occurs exclusively in adults (1-3% of total).
For celiac disease in children, steroids are almost never needed.