Gastrointestinal Disorders PDF

Gastrointestinal Disorders Wikimedia Commons, 2024 1. Anatomy of the GI tract Divided into upper and lower portions Mouth Esophagus Stomach (fundus, cardia, body, pylorus) Mucosal Parietal Chief (pepsinogen) Endocrin...

Gastrointestinal Disorders Wikimedia Commons, 2024 1. Anatomy of the GI tract Divided into upper and lower portions Mouth Esophagus Stomach (fundus, cardia, body, pylorus) Mucosal Parietal Chief (pepsinogen) Endocrine cells (gastrin) Small intestine (duodenum, jejunum and ileum) Large intestine (cecum, ascending, transverse, descending, sigmoid colon and rectum) Important roles in digestion Pancreas, liver and gallbladder Wikimedia Commons, 2024  2. Physiology of the GI tract Purpose: ingestion/digestion/absorption Categories of nutrients Carbohydrates Amylase in oral cavity; amylase from pancreas; enzymes from brush border Proteins (completed in the duodenum) Gastrin; hydrochloric acid converts pepsinogen to pepsin (chyme) Cholecystokinin in small intestine- pancreatic enzymes (e.g., trypsinogen) Lipids Cholecystokinin stimulates the gallbladder (bile) and pancreas and small intestine (lipase) Wikimedia Commons, 2024 3. Peptic Ulcers Break in mucosa in stomach or duodenum Potential of perforation Wikimedia Commons, 2024 Duodenal and gastric ulcers are commonly caused by Helicobacter pylori Stimulates the inflammatory process Increase in hydrochloric acid Production of urease Transmission (e.g., person-to-person, fecal-to-oral, contaminated food) Laboratory considerations Gastroscopy, breath tests, stool antigen tests, serological tests 3.1 GI Ulcers - Diagnosis Gastroscopy Tissue samples Rapid urease test (phenol red; changes in colour) Microbiological cultures Histologic tests Urea breath test High sensitivity (94%) and high specificity (98%) Most widely used test (noninvasive) Commonly uses urea with carbon-13 Pathogenic H. pylori produces urease Breaks down urea and release CO2 Elevated levels of labeled CO2 H. pylori Detect active infections (treatment monitoring) 3.1 GI Ulcers - Diagnosis Stool tests for H. pylori antigen Reliable, convenient, and noninvasive test High sensitivity and specificity (>90%) Detect active/ recent infections Use of immunoassays (ELISA) Serological tests Antibodies (IgM, IgA, IgG) to H. pylori 4. Zollinger-Ellison Syndrome Associated with mutations Benign, non-beta-islet cell, gastrin-secreting tumours Gastrinomas (pancreas or duodenum) Stimulate excess hydrochloric acid Peptic ulcers in stomach and duodenum May become malignant Symptoms/signs Gastric pain Fulminant peptic ulcers Massive gastric hypersecretion World J Clin Cases. Sep 16, 2023; 11(26): 6223-6230 Hypergastrinemia Diarrhea Steatorrhea 4.1 Zollinger-Ellison Syndrome- Diagnosis Gastrin levels Immunoassay techniques Gastrin levels >10 X RI + gastric acid hypersecretion (diagnostic-gastrinoma) Fasting gastrin levels Good prognostic value Imaging techniques (CT scan) Gastroscopy H. pylori investigation Negative 5. Malabsorption Syndrome Defective absorption of nutrients Single nutrient or all nutrients Single nutrient malabsorption Lactase deficiency Consequence – excretion of lactose Widespread nutrient deficiency E.g., Crohn disease, Celiac disease Common symptoms Diarrhea, abdominal discomfort, and weight loss Pixabay.com 5.1 Malabsorption Syndrome- Diagnosis Diagnostic tests may include: CBC Prothrombin time Vitamin and mineral assays Serologic tests (celiac disease) Pancreatic elastase-1 (maldigestion Vs. malabsorption) Stool cultures (bacteria? Parasites?) Fecal fat test (nonspecific) Lactose tolerance test No significant increase in blood glucose 6. Diarrhea Loose, watery, and frequent stools Chronic when more than 4 weeks Diarrhea ❖Acute Bacterial, parasitic, viral causes, antibiotics ❖Chronic May lead to: dehydration and low potassium levels Pixabay.com Causes: Inflammatory bowel disease Irritable bowel syndrome Celiac disease Food intolerances (E.g., lactose) Chemotherapy, radiation 6.1 Laboratory Tests for Diarrhea Stool cultures Immunoassays C. difficile, rotavirus, and E. coli strains Ova and parasite test Fecal fat test (nonspecific) 7. Inflammatory Bowel Disease (IBD) ❖Ulcerative colitis ❖Crohn disease Unknown cause (autoimmune, genetic link, medication, infectious agents?) Both exhibit bouts of remission and exacerbations Symptoms Abdominal pain Cramping Anorexia Bloody diarrhea Anemia 7.1 Crohn Disease X Ulcerative Colitis Characteristics of Crohn disease and ulcerative colitis Specific characteristic Crohn disease Ulcerative colitis Area affected More common in Rectum, colon terminal ileum and colon Stool Loose, semiformed Frequent, watery, with blood and mucus Lesion distribution Transmural, all layers Mucosa only Skip lesions diffuse Presence of granuloma Common No Fistula, fissure, abscess Common No Stricture, obstruction Common Rare Malabsorption Yes Not common 7.2 Inflammatory Bowel Disease- Diagnosis CBC (WBC) C-reactive protein Calprotectin stool test High (Inflammation) Fecal examination Red and white blood cells Occult blood tests Imaging (e.g., MRI) and endoscopy/ biopsy 8. Celiac Disease Autoimmune disease Different from allergies Antibodies to gluten (gliadin) Inflammation, malabsorption Avoided through a gluten-free diet Diagnosis Signs and symptoms are important Biopsy (gold standard) -invasive Wikimedia Commons, 2024 Endoscopy Villus atrophy Serological tests https://youtu.be/m_lt-h70DKw?si=0J90rTkSQmYBz9vs 8.1 Celiac Disease- Diagnosis Serological tests: IgA-antiendomysial antibody (EMA) Method: Immunofluorescence on monkey esophagus or human umbilical cord IgA-antigliadin antibody (AGA) Method: Quantitative ELISA IgA-antitissue transglutaminase antibody (tTG) Method: Quantitative ELISA IgA- deamidated gliadin peptide antibody (DGP) Method: Quantitative ELISA Wikimedia Commons, 2024 9. Gastrointestinal Function Tests Evaluate the function of the digestive system Identify abnormalities ❖Fecal fat test E.g., pancreatitis, celiac disease, cystic fibrosis Sudan stain Quantitative 72-hour stool collection Fat content ❖24-hour pH monitoring ❖D-Xylose absorption test Easily absorbed in intestine Found in urine and blood Intestinal or non-intestinal malabsorption? E.g., celiac disease, small intestinal bacterial overgrowth, pancreatic insufficiency Oral administration and multiple urine sample collection