OVERVIEW

What is celiac disease?

Celiac disease, also known as gluten-sensitive enteropathy, non-tropical sprue, or idiopathic steatorrhea, is an immune-mediated disorder with a genetic predisposition.

Patients cannot tolerate gliadin in gluten. When consuming gluten from wheat, barley, rye, or other foods, it triggers an immune response that damages the intestinal villi, leading to malabsorption in the small intestine. This ultimately results in a chronic inflammatory disorder of the small intestine, causing impaired absorption of multiple nutrients.

This malabsorption is often accompanied by diarrhea, hence the name "celiac disease."

Is celiac disease a genetic disorder?

Research indicates that celiac disease is clearly associated with genetic factors. It is closely linked to HLA-DQ2 and HLA-DQ8, located in the HLA class II D region of chromosome 6. Approximately 95% of celiac disease patients carry HLA-DQ2.

The prevalence of celiac disease among first-degree relatives of affected infants and young children is 2%–3%, and about 70% of identical twins share the condition, further confirming its genetic association.

SYMPTOMS

What are the symptoms and manifestations of celiac disease?

• Celiac disease in infants and young children mainly presents with abdominal distension, abdominal pain, chronic diarrhea (steatorrhea), constipation, vomiting, weight loss, and irritability. It may also lead to malnutrition, short stature, developmental delays, and enamel hypoplasia.

• Celiac disease in adults:

• Common digestive symptoms include nausea, vomiting, loss of appetite, bloating, and diarrhea, with stools often appearing oily and floating on the toilet water. Many patients may not exhibit obvious digestive symptoms or may present with extraintestinal symptoms.

• Extraintestinal symptoms may include unexplained iron-deficiency anemia, fatigue, bone and joint pain, arthritis, osteoporosis, depression or anxiety, numbness in the hands and feet, hypocalcemic seizures, mouth ulcers, and dermatitis herpetiformis.

CAUSES

What are the pathogenic factors of celiac disease?

There are three main pathogenic factors for celiac disease:

• Gluten gliadin in food is the pathogenic antigen of celiac disease. Gliadin is rich in glutamine and proline, with proline acting as an immune response activator in celiac disease, increasing intestinal mucosal permeability.

• Genetic factors play a significant role in celiac disease, leading to a deficiency of gliadin-degrading enzymes in the intestinal mucosa, impairing immune function, and triggering allergic reactions to gluten.

• Studies have found that repeated rotavirus infections can increase the risk of autoimmune celiac disease in genetically susceptible children. Additionally, multiple infections during infancy may also elevate the risk of developing celiac disease.

Which groups are more prone to celiac disease?

Celiac disease can occur at any age, often developing in childhood, with a peak incidence in adults between 40 and 50 years old. About 20% of patients are diagnosed with celiac disease at age >60. It is more common in women than in men, with a male-to-female ratio of 1:2–3.

DIAGNOSIS

What laboratory abnormalities are seen in celiac disease patients?

• Serological tests: IgA endomysial antibody (IgA EMA) has a specificity of up to 100% and is unique to celiac disease. The sensitivity and specificity of IgA tissue transglutaminase antibody (IgA tTG) for diagnosing celiac disease are 90%–98% and 95%–97%, respectively.

• Imaging studies: Gastrointestinal contrast studies or small bowel enemas may show segmentation, dilation, loss of normal fine feathery mucosal patterns, edematous folds, or ileal jejunization.

• Hematological and biochemical tests: Celiac disease patients may exhibit deficiencies in iron, folate, calcium, and vitamin D, with iron-deficiency anemia being the most common.

• Genetic testing: 95% of celiac disease patients carry the HLA-DQ2 or HLA-DQ8 alleles.

How is celiac disease diagnosed?

When a patient presents with suspicious clinical symptoms (e.g., chronic diarrhea or other gastrointestinal manifestations) and laboratory findings suggestive of malabsorption (e.g., iron, calcium, or folate deficiency), celiac disease should be considered. A family history of the disease can provide valuable clues.

Iron deficiency in the absence of obvious gastrointestinal bleeding should raise strong suspicion for celiac disease.

Key diagnostic steps for suspected celiac disease include:

• Small intestinal mucosal biopsy: Endoscopy may reveal marked duodenal villous atrophy, scalloped folds, or flattened folds that diminish or disappear upon air insufflation. Histopathology typically shows mucosal flattening with complete villous loss, increased epithelial apoptosis, and crypt hyperplasia. Capsule endoscopy may also be used to evaluate small bowel mucosal changes if needed.

• Antibody testing: IgA tTG and IgA EMA testing. Intestinal biopsy is mandatory if either antibody is positive. Antibody titers typically decline significantly after gluten withdrawal.

• Dietary trial: Symptoms gradually resolve after eliminating all gluten-containing foods. However, dietary therapy is generally avoided before obtaining a mucosal biopsy, as symptom improvement makes it difficult to distinguish between spontaneous recovery and treatment effects.

• Gluten challenge: Reintroducing gluten-containing foods leads to recurrence of small intestinal pathology, confirming the diagnosis.

What diseases should celiac disease be differentiated from?

• Irritable bowel syndrome (IBS): IBS is a functional disorder characterized by recurrent abdominal pain relieved by defecation, altered bowel habits, and changes in stool appearance during episodes. Unlike celiac disease, IBS does not cause malabsorption or mucosal abnormalities.

• Ulcerative colitis: This primarily affects the rectum and colon, presenting with chronic diarrhea, bloody mucopurulent stools, and abdominal pain. Severe cases may involve >10 bloody bowel movements daily. Colonoscopy is key for differentiation.

• Crohn’s disease: This commonly involves the terminal ileum, manifesting as abdominal pain, diarrhea, palpable masses, and sometimes bloody mucopurulent stools.

TREATMENT

Which department should patients with celiac disease visit?

Patients with celiac disease usually have a long course of illness and are advised to visit the gastroenterology department of a large tertiary hospital. In case of emergencies such as dehydration, severe abdominal pain, or bloating, they should immediately go to the emergency department.

Under what circumstances should a patient with celiac disease seek immediate medical attention?

If celiac disease causes severe dehydration (e.g., thirst, sunken eyes, reduced urine output), severe abdominal pain or bloating, or an inability to eat or drink, the patient should seek immediate medical attention.

How should celiac disease be treated?

The core treatment for celiac disease is a lifelong strict gluten-free diet, which excludes wheat, barley, and rye. Special attention should be paid to hidden sources of gluten, including hydrolyzed protein, food starch, malt flavoring, vegetable gum, and natural flavorings.

A gluten-free diet often leads to deficiencies in vitamins and minerals, such as folate, vitamin B12, fat-soluble vitamins, iron, and calcium. Therefore, additional vitamin and mineral supplementation should be provided alongside strict dietary therapy.

What are some effective antidiarrheal medications for diarrhea in celiac disease?

Frequent diarrhea can significantly reduce a patient's quality of life, and watery diarrhea may lead to fluid and electrolyte imbalances. Therefore, antidiarrheal medications should be used when necessary. Patients with mild diarrhea can take medications like smectite powder.

Patients with severe diarrhea may use drugs such as diphenoxylate or loperamide, with dosages adjusted based on the severity of diarrhea.

Can celiac disease be cured?

Most patients with celiac disease can achieve remission with a gluten-free diet, except for a small number with severe small intestinal villi damage who may not respond to dietary therapy.

Therefore, patients who do not improve with dietary treatment require regular health monitoring.

Is celiac disease a dangerous condition?

Celiac disease is not inherently dangerous, but delayed diagnosis can lead to prolonged symptoms. Most patients show significant improvement after diagnosis. However, celiac disease has been associated with an increased risk of certain cancers, such as intestinal lymphoma.

Additionally, celiac disease may coexist with other immune-related conditions, such as autoimmune thyroiditis, which should also be screened for.

DIET & LIFESTYLE

The pathogenic antigen of celiac disease is gluten in food. Which foods are high in gluten?

Gluten is mainly found in the seeds of wheat-based foods (such as wheat, barley, rye, hulless barley, oats, etc.), with wheat containing the highest amount.

China is a major consumer of wheat, and wheat-based foods play a significant role in daily life. However, this poses a serious threat to celiac disease patients, as even trace amounts of gluten can trigger the condition, severely impacting their quality of life.

How should celiac disease patients choose food?

Celiac disease patients should avoid all wheat-based foods, including bread, steamed buns, noodles, biscuits, pastries made from wheat flour, and puffed snacks. Extra caution is needed when dining out—foods like pizza, pasta, macaroni, and desserts should be avoided.

For staple foods, celiac disease patients can opt for starchy alternatives such as rice, millet, sorghum, red beans, mung beans, corn, and sweet potatoes. Symptoms usually improve within two weeks of adopting a gluten-free diet.

PREVENTION

How to Prevent Celiac Disease?

Celiac disease is an inflammatory disorder triggered by gluten, leading to malabsorption of multiple nutrients. The most critical measure is lifelong adherence to a gluten-free diet for prevention. Foods containing wheat, barley, and rye must be eliminated.

Gluten may also be present in certain medications, vitamins, and lip balms, so hidden sources require special attention. Safe options include corn, rice, legumes, meat, fish, dairy, vegetables, fruits, potatoes, and sweet potatoes.