? I. Introduction to the Department of Gastroenterology

Full Name: Department of Gastroenterology
Core Responsibilities: Diagnosing and treating diseases of the digestive system organs including the esophagus, stomach, intestines, liver, gallbladder, and pancreas.

✅ Common Scope of Diagnosis and Treatment:

• Gastritis, gastric ulcer, gastroesophageal reflux disease (GERD)

• Irritable bowel syndrome (IBS), inflammatory bowel disease (IBD, e.g., Crohn’s disease, ulcerative colitis)

• Hepatitis, fatty liver, liver cirrhosis

• Cholecystitis, gallstones, pancreatitis

• Gastrointestinal tumors: screening for gastric cancer and colorectal cancer

• Functional gastrointestinal disorders and allergic gastrointestinal diseases(e.g., allergic gastroenteritis)

? II. What is Allergic Gastroenteritis?

? Medical Name:

• Food Allergic Gastroenteritis

• Also known as food protein-induced gastrointestinal allergy(e.g., cow’s milk protein allergy, soy protein allergy)

It is a disease in which the immune system mounts an abnormal response to specific food proteins, leading to gastrointestinal inflammation and functional disorders.

⚠️ Note: Allergic gastroenteritis is not ordinary gastroenteritis (caused by bacterial or viral infections, for example), but a manifestation of allergic diseases in the digestive tract.。

? Pathogenesis:

When a person with an atopic diathesis ingests a certain food (e.g., milk, eggs, seafood, nuts) → the immune system misidentifies it as a "foreign invader" → releases inflammatory mediators such as histamine → causes edema of the gastrointestinal mucosa, accelerated peristalsis, and abnormal secretion → results in symptoms such as abdominal pain, diarrhea, and vomiting.

? III. Main Types and Clinical Manifestations

Allergic gastroenteritis is divided into two types based on the onset speed and pathogenesis:

1. IgE-mediated Type (Immediate-onset)

• Characteristics: Onset occurs rapidly within a few minutes to 2 hours after ingestion.

• Symptoms:

• Nausea, vomiting

• Abdominal pain, diarrhea

• May be accompanied by cutaneous symptoms (urticaria, lip swelling)

• Anaphylactic shock (dyspnea, hypotension) may occur in severe cases.

✅  Commonly triggered by highly allergenic foods such as peanuts, nuts, seafood, and eggs.

2. Non-IgE-mediated Type (Delayed-onset)

• Characteristics: Symptoms appear several hours or even 1-2 days after ingestion.

• Symptoms:

• Chronic diarrhea (may contain mucus or streaks of blood)

• Abdominal distension, abdominal pain

• Vomiting, food refusal

• Growth retardation (common in children)

• Malnutrition, anemia

✅  Commonly caused by cow’s milk protein allergy and soy protein allergy, and mostly seen in infants and young children.

? IV. High-Risk Groups

? V. How to Diagnose? – Common Examinations in Gastroenterology

1. Detailed Medical History + Dietary Log

• Record the temporal correlation between food intake and symptom onset

• Does the symptom always occur after consuming specific foods?

2. Allergen Testing

• Skin Prick Test: Applicable for IgE-mediated type

• Serum Specific IgE Test: Measures the antibody level to a specific food

3. Elimination Method: Food Elimination-Challenge Test(Gold Standard)

• Elimination Method: Discontinue the suspected food for 2–4 weeks and observe if symptoms alleviate

• Challenge Phase: Reintroduce the food and observe if symptoms recur

• ✅ This test must be performed under medical supervision to avoid severe allergic reactions!

4. Gastroscopy and Colonoscopy(When Necessary)

• A biopsy is taken to check for eosinophilic infiltration of the gastrointestinal mucosa (e.g., in eosinophilic gastroenteritis).

5. Fecal Examination

• Rule out infectious diarrhea

• Detect occult blood and white blood cells

? VI. Treatment Methods

1. Root Cause Treatment: Avoid Allergenic Foods

• Strict avoidance is mandatory after the allergenic food is identified.

• Common Allergenic Foods:

• Milk, eggs, peanuts, tree nuts

• Soy, wheat, seafood, fish

✅ For infants and young children with cow’s milk protein allergy, switch to extensively hydrolyzed formula or amino acid-based formula.

2. Nutritional Support

• Ensure adequate intake of nutrients such as protein, calcium and vitamin D.

• Supplement with formula for special medical purposes under the guidance of a dietitian when necessary.

3. Pharmacological Therapy(Symptomatic Treatment)

• Antihistamines: Alleviate mild allergic symptoms

• Intestinal Modulators: e.g., probiotics (certain strains can regulate immunity)

• Glucocorticoids: Used only for severe cases (e.g., eosinophilic gastroenteritis)

• Epinephrine: For emergency use in anaphylactic shock (e.g., EpiPen)

4. Desensitization Therapy (Immunotherapy)

• Currently still in the research stage. Some hospitals carry out Oral Immunotherapy (OIT), which induces immune tolerance by gradually increasing the intake of the allergen in small doses.

• This therapy must be conducted under close monitoring in a specialized hospital.

? VII. Differentiation from Other Diseases

? Key Distinction: Allergic gastroenteritis is often accompanied by other allergic manifestations(e.g., eczema, rhinitis, asthma).

? VIII. When to Consult a Gastroenterologist?

Seek medical attention promptly if you or your child experience the following symptoms:

• Abdominal pain, vomiting or diarrhea after eating a specific food every time

• Recurrent diarrhea, milk refusal and poor growth in infants

• Chronic abdominal distension with mucus or streaks of blood in stool

• Known food allergy with poorly controlled digestive symptoms

• The need to confirm a food allergy diagnosis and receive standardized management