Updated: Sep 2, 2009
Celiac disease (CD) 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), 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. Three cereals contain gluten and are toxic for patients with celiac disease: wheat, rye, and barley.
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.
Because the historical prevalence and long-term outcome of undiagnosed celiac disease were unknown, Rubio-Tapia et al collected serological information on 3 cohorts.2 These included 9,133 healthy young adults from whom sera were collected between 1948-1954 and 12,768 gender-matched subjects from 2 recent cohorts, one whose years of birth were similar to those of members of the first cohort, and one in which age at sampling was similar. Sera was tested for tissue transglutaminase and, if abnormal, for endomysial antibodies.
In the older cohort, during 45 years of follow-up, all-cause mortality was nearly 4-fold greater in persons with undiagnosed celiac disease than among those who were seronegative (hazard ratio = 3.9; 95% confidence interval, 2-7.5; P < 0.001). Comparison of the older and newer cohorts suggested that undiagnosed celiac disease in the United States has dramatically increased in the past half century; 0.2% of the older cohort had undiagnosed celiac disease compared with 0.8% ofthe cohort with similar years of birth and 0.9% of those with similar age at sampling (P ≤ .0001).
Pathogenesis
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.
Innate immunity
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.3
Adaptive immunity
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.
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.
Relevant anatomy
Celiac disease primarily affects the small intestine. This organ is schematically divided into 3 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 3 parts share similar tissue architecture and are responsible for most of the body's nutrient absorption. The intestinal wall has 4 layers, which (from the lumen inward) are termed the mucosa, submucosa, muscularis, and serosa. The 2 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.
Pathology
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.4 The histological changes of celiac disease are classified as follows:
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.5 Screening studies have shown that celiac disease has a very high prevalence, occurring in almost 1% of the general population throughout North America.
Celiac disease is as common in Europe as it is in North America; recent estimates suggest the prevalence in Europe is actually increasing,6 as is the prevalence of other autoimmune conditions, possibly as a result of the reduced exposure in early life to environmental bacterial stimuli (the "hygiene hypothesis").7
The prevalence of celiac disease in other areas of the world has been less studied. However, data are available from Latin America, North Africa, the Near East and Middle East, and northwest India; celiac disease has been reported in these areas, and prevalence data did not significantly differ from that seen in Europe and North America. A notable exception is represented by the Sub-Saharan African population, where an astounding prevalence of 5% has been reported.8 Thus, celiac disease constitutes one of the most common genetically induced chronic diseases worldwide.
However, celiac disease is considered extremely rare in people of African, Chinese, or Japanese descent, in whom the prevalence of the HLA haplotypes DQ2 and DQ8 is negligible.
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.9 Some indirect epidemiological evidence suggests that intestinal malignancies can be a cause of death in patients with undiagnosed celiac disease.10
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.
Clinical presentation
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.
Typical presentation
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.11 GI symptoms in older children are typically less evident and include nausea, recurrent abdominal pain, bloating, constipation, and intermittent diarrhea.
Atypical presentation
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.
Associated diseases
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.
Examination findings depend on extent of celiac disease.
Protein Intolerance
Mucosal biopsy of the duodenum shows the changes described above.
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.21 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.
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 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.
See Medical Care.
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.
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.
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.
100-500 mg IV q12h
20-120 mg/m2 IV/IM q12h or 0.67-4 mg/kg IV/IM q12h
CYP450 2D6 and 3A3/4 substrate; corticosteroid clearance may increase with phenytoin, barbiturates, or rifampin treatment or decrease with estrogens; cholestyramine may decrease AUC; corticosteroids may increase digitalis toxicity secondary to hypokalemia; coadministration with potassium depleting agents (eg, diuretics) may increase risk of hypokalemia; corticosteroids may decrease growth-promoting effect of GH; decreases effects of salicylates and vaccines used for immunization; monitor for hypokalemia with coadministration of diuretics or amphotericin B; antagonizes effects of anticholinergics; may increase anticoagulant effects of warfarin; decreases hypoglycemic effects of sulfonylureas and insulin; increases toxicity of cyclosporine
Active bacterial infection, chickenpox, measles or concurrent immunosuppressant therapy; avoid in patients with HIV, tubercular infection, congestive heart failure, renal disease, diabetes, or myasthenia gravis
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Compare dose for surface area to dose for weight to avoid overdose in overweight child (good rule is use former if weight dose higher); typical child with sprue is severely malnourished and underweight, so mg/kg should present no problem; avoid prolonged use (ie, >1 wk) in children without checking growth parameters and adrenal function; caution in hyperthyroidism, osteoporosis, peptic ulcer, cirrhosis, nonspecific ulcerative colitis, diabetes, and myasthenia gravis
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celiac sprue, celiac disease, gluten-sensitive enteropathy, nontropical sprue, wheat, potbelly, rye, barley, osteopenia, osteoporosis, short stature, delayed puberty, anemia, intestinal T-cell lymphoma, diarrhea, abdominal distension, malnutrition, celiac crisis, explosive watery diarrhea, dehydration, hypotension, hypokalemia, constipation, failure to thrive, dermatitis herpetiformis, dental enamel hypoplasia, iron-deficiency anemia, chronic hepatitis, hypertransaminasemia, arthritis, arthralgia, Down syndrome, Williams syndrome, Turner syndrome, diabetes mellitus type 1, alopecia, thyroiditis, rotavirus
Stefano Guandalini, MD, Director, University of Chicago Celiac Disease Program, Section Chief of Gastroenterology, Hepatology and Nutrition; Professor, Department of Pediatrics, University of Chicago Comer Children's Hospital
Stefano Guandalini, MD is a member of the following medical societies: American Gastroenterological Association, European Society for Paediatric Gastroenterology, Hepatology & Nutrition, and North American Society for Pediatric Gastroenterology and Nutrition
Disclosure: Nothing to disclose.
Phyllis A Vallee, MD, Associate Program Director, Department of Emergency Medicine, Henry Ford Hospital
Phyllis A Vallee, MD is a member of the following medical societies: American Academy of Emergency Medicine, American Medical Association, and Michigan State Medical Society
Disclosure: Nothing to disclose.
Jorge H Vargas, MD, Professor of Pediatrics and Clinical Professor of Pediatric Gastroenterology, David Geffen School of Medicine, University of California at Los Angeles; Consulting Physician, Department of Pediatrics, University of California at Los Angeles Health System
Jorge H Vargas, MD is a member of the following medical societies: American Liver Foundation, American Society for Gastrointestinal Endoscopy, American Society for Parenteral and Enteral Nutrition, Latin American Society of Pediatric Gastroenterology, Hepatology & Nutrition, and North American Society for Pediatric Gastroenterology and Nutrition
Disclosure: Nothing to disclose.
Mary L Windle, PharmD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy, Pharmacy Editor, eMedicine
Disclosure: Pfizer Inc Stock Investment from financial planner; Avanir Pharma Stock Investment from financial planner ; WebMD Salary and stock Employment and investment from financial planner
Carmen Cuffari, MD, Associate Professor, Department of Pediatrics, Division of Gastroenterology/Nutrition, Johns Hopkins University School of Medicine
Carmen Cuffari, MD is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, and Royal College of Physicians and Surgeons of Canada
Disclosure: Nothing to disclose.
Steven M Schwarz, MD, FAAP, FACN, AGAF, Professor of Pediatrics, Children's Hospital at Downstate, SUNY-Downstate Medical Center
Steven M Schwarz, MD, FAAP, FACN, AGAF is a member of the following medical societies: American Academy of Pediatrics, American College of Nutrition, American College of Physician Executives, American Gastroenterological Association, American Pediatric Society, Gastroenterology Research Group, New York Academy of Medicine, North American Society for Pediatric Gastroenterology and Nutrition, and Society for Pediatric Research
Disclosure: TAP Pharmaceuticals Honoraria Speaking and teaching; Curemark, LLC Consulting fee Board membership; Centocor, Inc. Grant/research funds Independent contractor
Carmen Cuffari, MD, Associate Professor, Department of Pediatrics, Division of Gastroenterology/Nutrition, Johns Hopkins University School of Medicine
Carmen Cuffari, MD is a member of the following medical societies: American College of Gastroenterology, American Gastroenterological Association, North American Society for Pediatric Gastroenterology, Hepatology and Nutrition, and Royal College of Physicians and Surgeons of Canada
Disclosure: Nothing to disclose.