The document classifies gastrointestinal diseases into 8 categories: 1) impaired digestion and absorption, 2) altered secretion, 3) altered gut transit, 4) immune dysregulation, 5) impaired gut blood flow, 6) neoplastic degeneration, 7) disorders without obvious organic abnormalities, and 8) genetic influences. It then provides examples and descriptions of diseases that fall into several of these categories.
The document classifies gastrointestinal diseases into 8 categories: 1) impaired digestion and absorption, 2) altered secretion, 3) altered gut transit, 4) immune dysregulation, 5) impaired gut blood flow, 6) neoplastic degeneration, 7) disorders without obvious organic abnormalities, and 8) genetic influences. It then provides examples and descriptions of diseases that fall into several of these categories.
The document classifies gastrointestinal diseases into 8 categories: 1) impaired digestion and absorption, 2) altered secretion, 3) altered gut transit, 4) immune dysregulation, 5) impaired gut blood flow, 6) neoplastic degeneration, 7) disorders without obvious organic abnormalities, and 8) genetic influences. It then provides examples and descriptions of diseases that fall into several of these categories.
The document classifies gastrointestinal diseases into 8 categories: 1) impaired digestion and absorption, 2) altered secretion, 3) altered gut transit, 4) immune dysregulation, 5) impaired gut blood flow, 6) neoplastic degeneration, 7) disorders without obvious organic abnormalities, and 8) genetic influences. It then provides examples and descriptions of diseases that fall into several of these categories.
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GASTROINTESTINAL
SYSTEM Paul Tang, MD, DPAMS CLASSIFICATION OF GI DISEASES
1. Impaired Digestion and Absorption
2. Altered Secretion 3. Altered Gut Transit 4. Immune Dysregulation CLASSIFICATION OF GI DISEASES
5. Impaired Gut Blood Flow
6. Neoplastic Degeneration 7. Disorders without Obvious Organic Abnormalities 8. Genetic Influences Impaired Digestion and Absorption
Diseases of the stomach, intestine, biliary tree, and
pancreas can disrupt nutrient digestion and absorption Gastric hypersecretory conditions damage the intestinal mucosa and accelerate transit due to excess gastric acid The most common intestinal maldigestion syndrome, lactase deficiency, produces flatus and diarrhea after dairy product ingestion and has no other adverse outcomes Impaired Digestion and Absorption
Biliary obstruction from stricture or neoplasm may
impair fat digestion Impaired release of pancreatic enzymes in chronic pancreatitis or pancreatic cancer decreases intraluminal digestion and can lead to profound malnutrition Altered Secretion
Gastric acid hypersecretion occurs in Zollinger-
Ellison syndrome, G-cell hyperplasia, retained antrum syndrome, and in some individuals with duodenal ulcer disease Conversely, patients with atrophic gastritis or pernicious anemia release little or no gastric acid Inflammatory and infectious small-intestinal and colonic diseases produce fluid loss through impaired absorption or enhanced secretion but do not usually cause malnutrition Altered Gut Transit
Commonly secondary to mechanical obstruction
Acid-induced stricture or neoplasm can cause esophageal occlusion, gastric outlet obstruction Small-intestinal obstruction most commonly results from adhesions but may also occur with Crohn’s disease, radiation- or drug-induced strictures, and, less likely, malignancy. Altered Gut Transit
The most common cause of colonic obstruction is
colon cancer Inflammatory strictures can occur in inflammatory bowel disease, after certain infections, or with some drugs Altered Gut Transit
Retardation of propulsion also develops from
disordered gut motor function Achalasia is characterized by impaired esophageal body peristalsis and incomplete lower esophageal sphincter relaxation Altered Gut Transit
Gastroparesis is the symptomatic delay in gastric
emptying of solid or liquid meals Intestinal pseudoobstruction causes marked delays in small bowel transit due to injury to enteric nerves or intestinal smooth muscle Altered Gut Transit
Slow transit constipation is produced by diffusely
impaired colonic propulsion Constipation is also produced by outlet abnormalities (rectal prolapse, intussusception, or failure of anal relaxation upon attempted defecation) Altered Gut Transit
Rapid gastric emptying occurs in postvagotomy
dumping syndrome and with gastric hypersecretion Accelerated transit with hyperdefecation is noted in hyperthyroidism Immune Dysregulation
The mucosal inflammation of celiac disease results from
dietary ingestion of gluten-containing grains Eosinophilic gastroenteritis is an inflammatory condition with prominent mucosal eosinophils Ulcerative colitis and Crohn’s disease are disorders of uncertain etiology that produce mucosal injury primarily in the lower gut Immune Dysregulation
The microscopic colitides, lymphocytic and collagenous
colitis, exhibit colonic subepithelial infiltrates without visible mucosal damage Bacterial, viral, and protozoal organisms may produce ileitis or colitis in selected patient populations Impaired Gut Blood Flow
Intestinal and colonic ischemia, which are
consequences of arterial embolus; arterial thrombosis; Venous thrombosis; or hypoperfusion from dehydration, sepsis, hemorrhage, or reduced cardiac output Neoplastic Degeneration
Esophageal cancer develops with chronic acid reflux
or in those with an extensive alcohol or tobacco use history Small-intestinal neoplasms are rare and occur with underlying inflammatory disease Anal cancers may arise with prior anal infection or inflammation Neoplastic Degeneration
Pancreatic and biliary cancers elicit severe pain,
weight loss, and jaundice and have poor prognoses Hepatocellular carcinoma usually arises from chronic viral hepatitis or cirrhosis secondary to other causes Most GI cancers are epithelial-derived Disorders w/o Obvious Organic Abnormalities
The most common GI disorders show no
abnormalities on biochemical or structural testing include irritable bowel syndrome (IBS), functional dyspepsia, non-cardiac chest pain, and functional heartburn Exaggerated visceral sensory responses to noxious stimulation Disorders w/o Obvious Organic Abnormalities
Symptoms in some may result from altered processing
of visceral pain sensations in the central nervous system Patients with functional bowel abnormalities with severe symptoms may have significant emotional disturbances Abdominal Pain Abdominal pain results from GI disease and extra-intestinal conditions Visceral pain is generally midline in location and vague in character Parietal pain is localized and precisely described Common inflammatory diseases with pain include peptic ulcer, appendicitis, diverticulitis, IBD, and infectious enterocolitis. Abdominal Pain Other intra-abdominal causes of pain include gallstone disease and pancreatitis. Non-inflammatory visceral sources include mesenteric ischemia and neoplasia. The most common causes of abdominal pain are IBS and functional dyspepsia. Heartburn, Nausea & Vomiting
Heartburn, a burning substernal sensation is felt
to result from excess gastroesophageal reflux of acid Nausea and vomiting are caused by GI diseases, medications, toxins, acute and chronic infection, endocrine disorders, labyrinthine conditions, and central nervous system disease Heartburn, Nausea & Vomiting The best characterized GI etiologies relate to mechanical obstruction of the upper gut; however, disorders of propulsion including gastroparesis and intestinal pseudoobstruction also elicit prominent symptoms As with abdominal pain, IBS and functional dyspepsia commonly present with nausea and vomiting. Altered Bowel Habits
Common complaints of patients with GI disease
Constipation is reported as infrequent defecation, straining with defecation, passage of hard stools, or a sense of incomplete fecal evacuation Causes of constipation include obstruction, motor disorders of the colon, medications, and endocrine diseases such as hypothyroidism and hyperparathyroidism Altered Bowel Habits
Other etiologies include portal hypertensive
causes, malignancy, tears across the gastroesophageal junction, and vascular lesions. Fecal mucus is common in IBS, while pus characterizes inflammatory disease. Altered Bowel Habits
Diarrhea is reported as frequent defecation,
passage of loose or watery stools, fecal urgency or a similar sense of incomplete evacuation Steatorrhea develops with malabsorption GI Bleeding
Upper GI bleeding presents with melena or
hematemesis Lower GI bleeding produces passage of bright red or maroon stools Chronic slow GI bleeding may present with iron deficiency anemia The most common upper GI causes of bleeding are ulcer disease, gastroduodenitis, and esophagitis GI Bleeding
The most prevalent lower GI sources of
hemorrhage include hemorrhoids, anal fissures, diverticula, and arteriovenous malformations Other causes include neoplasm, IBD, ischemia, infectious colitis, and other vascular lesions GI Bleeding Upper Gastrointestinal Tract Lower Gastrointestinal Tract
• Melena or hematochezia • Passage of bright red or
maroon stools • The most common causes • Most prevalent lower GI are ulcer disease, sources of hemorrhage gastroduodenitis, and include hemorrhoids, anal esophagitis fissures, diverticula, and arteriovenous malformations • Other etiologies include • Other causes include portal hypertensive causes, neoplasm, IBD, ischemia, malignancy, tears across the infectious colitis, and other gastroesophageal junction, vascular lesions and vascular lesions